Investment Securities - Amortized Cost and Estimated Fair Value by Contractual Maturity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Available-for-sale securities, Amortized cost
Due in one year or less	$ 23,968
Due after one year through five years	53,138
Due after five years through 10 years	35,824
Due after 10 years	91,749
Amortized cost	204,679
Available-for-sale securities, Fair value
Due in one year or less	23,633
Due after one year through five years	51,312
Due after five years through 10 years	35,204
Due after 10 years	87,099
Fair value	$ 197,248	$ 205,857
Available-for-sale securities, Average yield
Due in one year or less	2.33%
Due after one year through five years	3.82%
Due after five years through 10 years	4.29%
Due after 10 years	4.43%
Average yield	4.00%
Total held-to-maturity securities, Amortized cost
Due in one year or less	$ 58,070
Due after one year through five years	80,351
Due after five years through 10 years	98,757
Due after 10 years	175,710
Amortized cost	412,888
Total held-to-maturity securities, Fair value
Due in one year or less	56,470
Due after one year through five years	75,592
Due after five years through 10 years	88,208
Due after 10 years	161,720
Fair value	$ 381,990	388,648
Total held-to-maturity securities, Average yield
Due in one year or less	0.46%
Due after one year through five years	0.91%
Due after five years through 10 years	2.25%
Due after 10 years	3.68%
Average yield	2.35%
Supplemental information
US government agencies and US government sponsored enterprises residential MBS estimated duration	7 years
Agency residential collateralized mortgage obligations estimated duration	6 years
Nonagency residential collateralized mortgage obligations estimated duration	6 years
Available for sale securities allowance for credit losses	$ 29
Portfolio layer fair value basis adjustments	21
Held-to-maturity securities allowance for credit losses	$ 61
Minimum
Supplemental information
Due period of mortgage-backed securities and collateralized mortgage obligations	10 years
Mortgage-backed securities
Available-for-sale securities, Amortized cost
Due in one year or less	$ 14
Due after one year through five years	3,406
Due after five years through 10 years	4,644
Due after 10 years	70,187
Amortized cost	78,251
Available-for-sale securities, Fair value
Due in one year or less	14
Due after one year through five years	3,259
Due after five years through 10 years	4,678
Due after 10 years	65,772
Fair value	$ 73,723	78,081
Available-for-sale securities, Average yield
Due in one year or less	2.14%
Due after one year through five years	4.16%
Due after five years through 10 years	5.69%
Due after 10 years	4.04%
Average yield	4.14%
Total held-to-maturity securities, Amortized cost
Due in one year or less	$ 99
Due after one year through five years	2,755
Due after five years through 10 years	11,506
Due after 10 years	119,996
Amortized cost	134,356
Total held-to-maturity securities, Fair value
Due in one year or less	96
Due after one year through five years	2,575
Due after five years through 10 years	10,332
Due after 10 years	107,666
Fair value	$ 120,669	118,717
Total held-to-maturity securities, Average yield
Due in one year or less	5.70%
Due after one year through five years	2.61%
Due after five years through 10 years	2.55%
Due after 10 years	2.98%
Average yield	2.94%
U.S. Treasury and government agencies
Available-for-sale securities, Amortized cost
Due in one year or less	$ 11,298
Due after one year through five years	45,163
Due after five years through 10 years	20,706
Due after 10 years	6,481
Amortized cost	83,648
Available-for-sale securities, Fair value
Due in one year or less	11,030
Due after one year through five years	43,602
Due after five years through 10 years	20,506
Due after 10 years	6,501
Fair value	$ 81,639	92,060
Available-for-sale securities, Average yield
Due in one year or less	0.36%
Due after one year through five years	3.87%
Due after five years through 10 years	4.33%
Due after 10 years	6.33%
Average yield	3.70%
Total held-to-maturity securities, Amortized cost
Due in one year or less	$ 57,971
Due after one year through five years	77,514
Due after five years through 10 years	67,002
Due after 10 years	0
Amortized cost	202,487
Total held-to-maturity securities, Fair value
Due in one year or less	56,374
Due after one year through five years	72,935
Due after five years through 10 years	57,903
Due after 10 years	0
Fair value	$ 187,212	189,100
Total held-to-maturity securities, Average yield
Due in one year or less	0.45%
Due after one year through five years	0.84%
Due after five years through 10 years	1.27%
Due after 10 years	0.00%
Average yield	0.87%
Obligations of U.S. states and municipalities
Available-for-sale securities, Amortized cost
Due in one year or less	$ 18
Due after one year through five years	140
Due after five years through 10 years	2,380
Due after 10 years	11,154
Amortized cost	13,692
Available-for-sale securities, Fair value
Due in one year or less	18
Due after one year through five years	142
Due after five years through 10 years	2,403
Due after 10 years	10,966
Fair value	$ 13,529	6,786
Available-for-sale securities, Average yield
Due in one year or less	4.84%
Due after one year through five years	4.51%
Due after five years through 10 years	4.46%
Due after 10 years	5.44%
Average yield	5.26%
Total held-to-maturity securities, Amortized cost
Due in one year or less	$ 0
Due after one year through five years	0
Due after five years through 10 years	738
Due after 10 years	11,595
Amortized cost	12,333
Total held-to-maturity securities, Fair value
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	711
Due after 10 years	10,900
Fair value	$ 11,611	18,720
Total held-to-maturity securities, Average yield
Due in one year or less	0.00%
Due after one year through five years	0.00%
Due after five years through 10 years	4.20%
Due after 10 years	4.06%
Average yield	4.06%
Non-U.S. government debt securities
Available-for-sale securities, Amortized cost
Due in one year or less	$ 12,348
Due after one year through five years	2,802
Due after five years through 10 years	4,436
Due after 10 years	374
Amortized cost	19,960
Available-for-sale securities, Fair value
Due in one year or less	12,339
Due after one year through five years	2,710
Due after five years through 10 years	4,006
Due after 10 years	375
Fair value	$ 19,430	19,696
Available-for-sale securities, Average yield
Due in one year or less	3.89%
Due after one year through five years	2.20%
Due after five years through 10 years	1.47%
Due after 10 years	3.51%
Average yield	3.11%
Corporate debt securities
Available-for-sale securities, Amortized cost
Due in one year or less	$ 187
Due after one year through five years	221
Due after five years through 10 years	13
Due after 10 years	0
Amortized cost	421
Available-for-sale securities, Fair value
Due in one year or less	134
Due after one year through five years	217
Due after five years through 10 years	13
Due after 10 years	0
Fair value	$ 364	$ 357
Available-for-sale securities, Average yield
Due in one year or less	15.98%
Due after one year through five years	11.40%
Due after five years through 10 years	6.11%
Due after 10 years	0.00%
Average yield	13.26%
Asset-backed securities
Available-for-sale securities, Amortized cost
Due in one year or less	$ 103
Due after one year through five years	1,406
Due after five years through 10 years	3,645
Due after 10 years	3,553
Amortized cost	8,707
Available-for-sale securities, Fair value
Due in one year or less	98
Due after one year through five years	1,382
Due after five years through 10 years	3,598
Due after 10 years	3,485
Fair value	$ 8,563
Available-for-sale securities, Average yield
Due in one year or less	5.25%
Due after one year through five years	3.13%
Due after five years through 10 years	5.52%
Due after 10 years	5.68%
Average yield	5.20%
Total held-to-maturity securities, Amortized cost
Due in one year or less	$ 0
Due after one year through five years	82
Due after five years through 10 years	19,511
Due after 10 years	44,119
Amortized cost	63,712
Total held-to-maturity securities, Fair value
Due in one year or less	0
Due after one year through five years	82
Due after five years through 10 years	19,262
Due after 10 years	43,154
Fair value	$ 62,498
Total held-to-maturity securities, Average yield
Due in one year or less	0.00%
Due after one year through five years	5.72%
Due after five years through 10 years	5.37%
Due after 10 years	5.48%
Average yield	5.45%