Capital - Actual Capital Amount and Ratios (Details)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Total
Excess, ratio	0.0714
Leverage Capital
Banking Regulation, Capital Conservation Buffer, Capital Conserved, Minimum	0.0464
Parent company
Common Equity Tier 1
Total capital, amount	$ 7,997,000,000	$ 8,009,000,000
Total capital, ratio	0.1183	0.0905
Minimum for capital adequacy, amount	$ 3,043,000,000	$ 3,983,000,000
Minimum for capital adequacy, ratio	0.0450	0.0450
Excess, amount	$ 4,954,000,000	$ 4,026,000,000
Excess, ratio	7.33%	4.55%
Tier 1
Total capital, amount	$ 8,501,000,000	$ 8,512,000,000
Total capital, ratio	0.1257	0.0962
Minimum for capital adequacy, amount	$ 4,057,000,000	$ 5,310,000,000
Minimum for capital adequacy, ratio	0.0600	0.0600
Excess, amount	$ 4,444,000,000	$ 3,202,000,000
Excess, ratio	0.0657	0.0362
Total
Total capital, amount	$ 10,238,000,000	$ 10,415,000,000
Total capital, ratio	0.1514	0.1177
Minimum for capital adequacy, amount	$ 5,409,000,000	$ 7,081,000,000
Minimum for capital adequacy, ratio	0.0800	0.0800
Excess, amount	$ 4,829,000,000	$ 3,334,000,000
Excess, ratio	0.0714	0.0377
Leverage Capital
Total capital, amount	$ 8,501,000,000	$ 8,512,000,000
Total capital, ratio	0.0768	0.0775
Minimum for capital adequacy, amount	$ 4,428,000,000	$ 4,392,000,000
Minimum for capital adequacy, ratio	0.0400	0.0400
Excess, amount	$ 4,073,000,000	$ 4,120,000,000
Excess, ratio	3.68%	3.75%
Subsidiaries
Common Equity Tier 1
Total capital, amount	$ 8,912,000,000	$ 9,305,000,000
Total capital, ratio	0.1321	0.1052
Minimum for capital adequacy, amount	$ 3,036,000,000	$ 3,980,000,000
Minimum for capital adequacy, ratio	0.0450	0.0450
Excess, amount	$ 5,876,000,000	$ 5,325,000,000
Excess, ratio	8.71%	6.02%
Tier 1
Total capital, amount	$ 8,912,000,000	$ 9,305,000,000
Total capital, ratio	0.1321	0.1052
Minimum for capital adequacy, amount	$ 4,048,000,000	$ 5,307,000,000
Minimum for capital adequacy, ratio	0.0600	0.0600
Excess, amount	$ 4,864,000,000	$ 3,998,000,000
Excess, ratio	0.0721	0.0452
Total
Total capital, amount	$ 9,760,000,000	$ 10,271,000,000
Total capital, ratio	0.1447	0.1161
Minimum for capital adequacy, amount	$ 5,398,000,000	$ 7,076,000,000
Minimum for capital adequacy, ratio	0.0800	0.0800
Excess, amount	$ 4,362,000,000	$ 3,195,000,000
Excess, ratio	0.0647	0.0361
Leverage Capital
Total capital, amount	$ 8,912,000,000	$ 9,305,000,000
Total capital, ratio	0.0805	0.0848
Minimum for capital adequacy, amount	$ 4,426,000,000	$ 4,389,000,000
Minimum for capital adequacy, ratio	0.0400	0.0400
Excess, amount	$ 4,486,000,000	$ 4,916,000,000
Excess, ratio	4.05%	4.48%