Segment reporting - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) segment	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)
Segment Reporting
Number of reportable segments \| segment			2
Total assets	$ 78,972,300	$ 76,065,090	$ 78,972,300	$ 76,065,090	$ 75,348,267
Total consolidated revenues	873,964	800,026	1,709,770	1,557,684
United States
Segment Reporting
Total assets	16,255,576		16,255,576		16,101,705
Total consolidated revenues	139,422	139,274	279,085	266,490
Other
Segment Reporting
Total assets	1,402,812		1,402,812		1,291,097
Total consolidated revenues	33,054	$ 24,520	61,126	45,001
BPPR \| United States
Segment Reporting
Bank loan origination					29,000
Total assets	1,200,000		1,200,000		1,400,000
Total consolidated revenues			42,000	51,400
BPPR \| United States \| Commercial multi-family
Segment Reporting
Total assets	101,000		101,000		102,000
BPPR \| United States \| Commercial real estate loans
Segment Reporting
Total assets	378,000		378,000		435,000
BPPR \| United States \| Commercial and industrial
Segment Reporting
Total assets	674,000		674,000		714,000
BPPR \| United States \| Unsecured personal loans
Segment Reporting
Total assets	23,000		23,000		41,000
BPPR \| Other
Segment Reporting
Total assets	$ 1,100,000		1,100,000		$ 1,000,000
Total consolidated revenues			$ 27,700	$ 25,000