Regulatory Capital Table - ERCF Capital Requirements (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2024
Compliance with Regulatory Capital Requirements - ERCF [Abstract]
Adjusted total assets		$ 3,905,000		$ 3,817,000
Risk-weighted assets (standardized approach)		1,231,000		1,118,000
Minimum Capital Requirement [Member]
Risk-based capital amounts [Abstract]
Total capital		99,000		89,000
CET1 capital		55,000		50,000
Tier 1 capital		74,000		67,000
Adjusted total capital		99,000		$ 89,000
Risk-based capital ratios [Abstract]
Total capital	8.00%		8.00%	8.00%
CET1 capital	4.50%		4.50%	4.50%
Tier 1 capital	6.00%		6.00%	6.00%
Adjusted total capital	8.00%		8.00%	8.00%
Leverage capital amounts: [Abstract]
Core capital		98,000		$ 95,000
Tier 1 capital		98,000		$ 95,000
Leverage capital ratios [Abstract]
Core capital			2.50%	2.50%
Tier 1 capital			2.50%	2.50%
Capital Requirement Including Buffer [Member]
Risk-based capital amounts [Abstract]
Total capital		99,000		$ 89,000
CET1 capital		114,000		107,000
Tier 1 capital		133,000		124,000
Adjusted total capital		158,000		$ 146,000
Risk-based capital ratios [Abstract]
Total capital			8.00%	8.00%
CET1 capital			9.30%	9.60%
Tier 1 capital			10.80%	11.10%
Adjusted total capital			12.80%	13.10%
Leverage capital amounts: [Abstract]
Core capital		98,000		$ 95,000
Tier 1 capital		113,000		$ 109,000
Leverage capital ratios [Abstract]
Core capital			2.50%	2.50%
Tier 1 capital			2.90%	2.90%
Available Capital (Deficit) [Member]
Risk-based capital amounts [Abstract]
Total capital		6,000		$ (6,000)
CET1 capital		(22,000)		(32,000)
Tier 1 capital		(7,000)		(18,000)
Adjusted total capital		(7,000)		$ (18,000)
Risk-based capital ratios [Abstract]
Total capital			0.50%	(0.50%)
CET1 capital			(1.80%)	(2.90%)
Tier 1 capital			(0.60%)	(1.60%)
Adjusted total capital			(0.60%)	(1.60%)
Leverage capital amounts: [Abstract]
Core capital		(2,000)		$ (13,000)
Tier 1 capital		$ (7,000)		$ (18,000)
Leverage capital ratios [Abstract]
Core capital			(0.10%)	(0.30%)
Tier 1 capital			(0.20%)	(0.50%)