Regulatory Capital Table - ERCF Capital Requirements (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Compliance with Regulatory Capital Requirements - ERCF [Abstract]
Adjusted total assets	$ 3,903,000	$ 3,905,000
Risk-weighted assets (standardized approach)	1,259,000	1,231,000
Available Capital (Deficit) [Member]
Risk-based capital amounts [Abstract]
Total capital (statutory)	9,000	6,000
CET1 capital	(18,000)	(22,000)
Tier 1 capital	(4,000)	(7,000)
Adjusted total capital	$ (4,000)	$ (7,000)
Risk-based capital ratios [Abstract]
Total capital (statutory)	0.70%	0.50%
CET1 capital	(1.40%)	(1.80%)
Tier 1 capital	(0.30%)	(0.60%)
Adjusted total capital	(0.30%)	(0.60%)
Leverage capital amounts: [Abstract]
Core capital (statutory)	$ 1,000	$ (2,000)
Tier 1 capital	$ (4,000)	$ (7,000)
Leverage capital ratios [Abstract]
Core capital (statutory)	0.00%	(0.10%)
Tier 1 capital	(0.10%)	(0.20%)
Minimum Capital Requirement [Member]
Risk-based capital amounts [Abstract]
Total capital (statutory)	$ 101,000	$ 99,000
CET1 capital	57,000	55,000
Tier 1 capital	76,000	74,000
Adjusted total capital	$ 101,000	$ 99,000
Risk-based capital ratios [Abstract]
Total capital (statutory)	8.00%	8.00%
CET1 capital	4.50%	4.50%
Tier 1 capital	6.00%	6.00%
Adjusted total capital	8.00%	8.00%
Leverage capital amounts: [Abstract]
Core capital (statutory)	$ 98,000	$ 98,000
Tier 1 capital	$ 98,000	$ 98,000
Leverage capital ratios [Abstract]
Core capital (statutory)	2.50%	2.50%
Tier 1 capital	2.50%	2.50%
Capital Requirement Including Buffer [Member]
Risk-based capital amounts [Abstract]
Total capital (statutory)	$ 101,000	$ 99,000
CET1 capital	117,000	114,000
Tier 1 capital	136,000	133,000
Adjusted total capital	$ 161,000	$ 158,000
Risk-based capital ratios [Abstract]
Total capital (statutory)	8.00%	8.00%
CET1 capital	9.30%	9.30%
Tier 1 capital	10.80%	10.80%
Adjusted total capital	12.80%	12.80%
Leverage capital amounts: [Abstract]
Core capital (statutory)	$ 98,000	$ 98,000
Tier 1 capital	$ 113,000	$ 113,000
Leverage capital ratios [Abstract]
Core capital (statutory)	2.50%	2.50%
Tier 1 capital	2.90%	2.90%