v3.26.1
Investment Securities (Tables)
6 Months Ended
Jun. 30, 2026
Investment Securities  
Schedule of amortized cost and fair value of investment securities held to maturity

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Gross

  ​ ​ ​

Gross

​

​

 

​

​

Amortized

​

Unrealized

​

Unrealized

​

Fair

 

(Dollars in thousands)

  ​ ​ ​

Cost

  ​ ​ ​

Gains

  ​ ​ ​

Losses

  ​ ​ ​

Value

 

June 30, 2026:

​

​

​

​

​

​

​

​

​

​

​

​

​

U.S. Government agencies

​

$

132,915

​

$

—

​

$

(16,795)

​

$

116,120

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

1,090,113

​

​

—

​

​

(175,475)

​

​

914,638

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

363,925

​

​

—

​

​

(57,204)

​

​

306,721

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

324,980

​

​

—

​

​

(57,187)

​

​

267,793

​

Small Business Administration loan-backed securities

​

​

43,821

​

​

—

​

​

(8,051)

​

​

35,770

​

​

​

$

1,955,754

​

$

—

​

$

(314,712)

​

$

1,641,042

​

December 31, 2025:

​

​

​

​

​

​

​

​

​

​

​

​

​

U.S. Government agencies

​

$

132,913

​

$

—

​

$

(15,767)

​

$

117,146

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

1,153,024

​

​

—

​

​

(177,101)

​

​

975,923

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

379,107

​

​

—

​

​

(55,232)

​

​

323,875

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

336,910

​

​

—

​

​

(58,332)

​

​

278,578

​

Small Business Administration loan-backed securities

​

​

46,076

​

​

—

​

​

(8,748)

​

​

37,328

​

​

​

$

2,048,030

​

$

—

​

$

(315,180)

​

$

1,732,850

​

Schedule of amortized cost and fair value of investment securities available for sale

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Gross

​

Gross

​

​

​

​

​

​

Amortized

​

Unrealized

​

Unrealized

​

Fair

 

(Dollars in thousands)

  ​ ​ ​

Cost

  ​ ​ ​

Gains

  ​ ​ ​

Losses

  ​ ​ ​

Value

 

June 30, 2026:

​

​

​

​

​

​

​

​

​

​

​

​

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

$

2,026,760

​

$

4,562

​

$

(144,756)

​

$

1,886,566

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

2,082,757

​

​

5,511

​

​

(54,109)

​

​

2,034,159

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

1,095,770

​

​

1,050

​

​

(79,341)

​

​

1,017,479

​

State and municipal obligations

​

 

1,240,617

​

 

2,484

​

 

(128,351)

​

 

1,114,750

​

Small Business Administration loan-backed securities

​

 

547,528

​

 

433

​

 

(24,844)

​

 

523,117

​

Corporate securities

​

​

23,000

​

​

—

​

​

(894)

​

​

22,106

​

​

​

$

7,016,432

​

$

14,040

​

$

(432,295)

​

$

6,598,177

​

December 31, 2025:

​

​

​

​

​

​

​

​

​

​

​

​

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

$

1,826,307

​

$

10,108

​

$

(138,307)

​

$

1,698,108

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

2,208,710

​

​

23,979

​

​

(47,105)

​

​

2,185,584

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

903,209

​

​

3,282

​

​

(74,042)

​

​

832,449

​

State and municipal obligations

​

 

1,141,377

​

 

1,252

​

 

(135,217)

​

 

1,007,412

​

Small Business Administration loan-backed securities

​

 

593,973

​

 

548

​

 

(26,088)

​

 

568,433

​

Corporate securities

​

​

23,000

​

​

—

​

​

(1,230)

​

​

21,770

​

​

​

$

6,696,576

​

$

39,169

​

$

(421,989)

​

$

6,313,756

​

Schedule of amortized cost and carrying value of other investment securities

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​

​

​

​

​

​

​

Carrying

 

(Dollars in thousands)

  ​ ​ ​

Value

 

June 30, 2026:

​

​

​

​

Federal Home Loan Bank stock

​

$

32,336

​

Federal Reserve Bank stock

​

​

234,374

​

Investment in unconsolidated subsidiaries

​

 

5,287

​

Other investment securities

​

 

94,989

​

​

​

$

366,986

​

December 31, 2025:

​

​

​

​

Federal Home Loan Bank stock

​

$

18,086

​

Federal Reserve Bank stock

​

​

234,374

​

Investment in unconsolidated subsidiaries

​

 

5,287

​

Other investment securities

​

 

95,681

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​

​

$

353,428

​

Schedule of amortized cost and fair value of debt securities by contractual maturity

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​

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​

Securities

​

Securities

 

​

​

Held to Maturity

​

Available for Sale

 

​

​

Amortized

​

Fair

​

Amortized

​

Fair

 

(Dollars in thousands)

  ​ ​ ​

Cost

  ​ ​ ​

Value

  ​ ​ ​

Cost

  ​ ​ ​

Value

 

Due in one year or less

  ​ ​ ​

$

—

​

$

—

  ​ ​ ​

$

25,660

  ​ ​ ​

$

25,525

​

Due after one year through five years

​

 

172,583

​

 

160,937

​

 

415,952

​

 

411,268

​

Due after five years through ten years

​

 

330,479

​

 

287,326

​

 

1,211,660

​

 

1,143,401

​

Due after ten years

​

 

1,452,692

​

 

1,192,779

​

 

5,363,160

​

 

5,017,983

​

​

​

$

1,955,754

​

$

1,641,042

​

$

7,016,432

​

$

6,598,177

​

Schedule of information with respect to sales of available-for-sale securities

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​

​

​

​

​

​

​

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​

​

​

​

​

​

​

​

2025

 

(Dollars in thousands)

​

Sales of Securities Acquired from Independent

​

Investment Securities Sales

​

Total

​

Sale proceeds

​

$

1,279,717

  ​ ​ ​

$

1,594,393

​

$

2,874,110

​

Gross realized gains

​

​

—

​

​

8,892

​

​

8,892

​

Gross realized losses

​

 

—

​

 

(237,703)

​

 

(237,703)

​

Net realized losses

​

$

—

​

$

(228,811)

​

$

(228,811)

​

Schedule of securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position

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​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Less Than

​

12 Months

 

​

​

12 Months

​

or More

 

​

​

Gross Unrealized

​

Fair

​

Gross Unrealized

​

Fair

 

(Dollars in thousands)

  ​ ​ ​

Losses

  ​ ​ ​

Value

  ​ ​ ​

Losses

  ​ ​ ​

Value

 

June 30, 2026:

​

​

​

​

​

​

​

​

​

​

​

​

​

Securities Held to Maturity

​

​

​

​

​

​

​

​

​

​

​

​

​

U.S. Government agencies

​

$

—

​

$

—

​

$

16,795

​

$

116,120

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

—

​

​

—

​

​

175,475

​

​

914,638

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

—

​

 

—

​

 

57,204

​

 

306,721

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

—

​

​

—

​

​

57,188

​

​

267,793

​

Small Business Administration loan-backed securities

​

​

—

​

​

—

​

​

8,050

​

​

35,770

​

​

​

$

—

​

$

—

​

$

314,712

​

$

1,641,042

​

Securities Available for Sale

​

​

​

​

​

​

​

​

​

​

​

​

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

$

5,882

​

$

694,570

​

$

138,873

​

$

752,869

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

5,713

​

 

874,273

​

 

48,396

​

 

258,069

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

 

4,740

​

​

462,508

​

​

74,602

​

​

391,176

​

State and municipal obligations

​

 

436

​

​

61,086

​

​

127,914

​

​

864,249

​

Small Business Administration loan-backed securities

​

 

403

​

​

126,057

​

​

24,442

​

​

358,963

​

Corporate securities

​

​

64

​

​

9,936

​

​

830

​

​

12,170

​

​

​

$

17,238

​

$

2,228,430

​

$

415,057

​

$

2,637,496

​

December 31, 2025:

​

​

​

​

​

​

​

​

​

​

​

​

​

Securities Held to Maturity

​

​

​

​

​

​

​

​

​

​

​

​

​

U.S. Government agencies

​

$

—

​

$

—

​

$

15,767

​

$

117,146

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

—

​

​

—

​

​

177,101

​

​

975,923

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

—

​

 

—

​

 

55,232

​

 

323,874

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

—

​

​

—

​

​

58,332

​

​

278,579

​

Small Business Administration loan-backed securities

​

​

—

​

​

—

​

​

8,748

​

​

37,328

​

​

​

$

—

​

$

—

​

$

315,180

​

$

1,732,850

​

Securities Available for Sale

​

​

​

​

​

​

​

​

​

​

​

​

​

Residential mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

$

459

​

$

145,357

​

$

137,848

​

$

803,407

​

Residential collateralized mortgage-obligations issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

46

​

 

40,399

​

 

47,059

​

 

278,620

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

 

228

​

​

152,299

​

​

73,814

​

​

423,165

​

State and municipal obligations

​

 

572

​

​

43,620

​

​

134,645

​

​

903,784

​

Small Business Administration loan-backed securities

​

 

680

​

​

284,036

​

​

25,408

​

​

202,322

​

Corporate securities

​

​

—

​

​

—

​

​

1,230

​

​

21,769

​

​

​

$

1,985

​

$

665,711

​

$

420,004

​

$

2,633,067

​

Schedule of trading securities

​

​

​

​

​

​

​

​

​

​

  ​ ​ ​

June 30,

​

December 31,

​

(Dollars in thousands)

  ​ ​ ​

2026

 

2025

​

U.S. Government agencies

​

$

9,855

​

$

1,872

​

Residential mortgage pass-through securities issued or guaranteed by U.S.

​

​

​

​

​

​

​

government agencies or sponsored enterprises

​

​

20,667

​

​

9,799

​

Other residential mortgage issued or guaranteed by U.S. government

​

 

​

​

 

​

​

agencies or sponsored enterprises

​

 

7,705

​

 

1,419

​

Commercial mortgage-backed securities issued by U.S. government

​

​

​

​

​

​

​

agencies or sponsored enterprises

​

​

28,073

​

​

5,966

​

State and municipal obligations

​

​

42,131

​

​

24,816

​

Small Business Administration asset-backed securities

​

​

82,421

​

​

66,173

​

Other debt securities

​

​

242

​

​

138

​

​

​

$

191,094

​

$

110,183

​

Summary of net gains (losses) on trading securities

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

  ​ ​ ​

Three Months Ended

​

Six Months Ended

​

​

​

June 30,

​

June 30,

​

(Dollars in thousands)

  ​ ​ ​

2026

 

2025

​

2026

​

2025

​

Net gains (losses) on sales transaction

​

$

1,017

​

$

(418)

​

$

1,401

​

$

(56)

​

Net unrealized gains (losses)

​

​

89

​

​

291

​

​

(487)

​

​

412

​

Net gains (losses) on trading securities

​

$

1,106

​

$

(127)

​

$

914

​

$

356

​