HTM Debt Securities, Contractual Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 267,214	$ 297,059
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	276
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	2,281
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	15,844
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	248,813
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	216,927	255,521
Held-to-maturity, fair value, remaining contractual maturity, due within one year	274
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	2,122
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	15,741
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 198,790
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.87%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	2.67%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	3.91%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	6.89%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.60%
Securities of U.S. Treasury and federal agencies [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 3,790	16,202
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	3,790
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	2,004	14,285
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 2,004
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	1.58%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	0.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	1.58%
Securities of U.S. states and political subdivisions [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 18,862	30,985
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	276
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	485
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	716
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	17,385
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	14,146	26,608
Held-to-maturity, fair value, remaining contractual maturity, due within one year	274
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	458
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	656
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 12,758
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.37%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	2.67%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	1.65%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	2.79%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.37%
Federal agency mortgage-backed securities [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 212,805	216,966
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	212,805
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	169,474	182,744
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	0
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 169,474
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.36%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	0.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.36%
Non-agency mortgage-backed securities [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 1,284	1,253
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	40
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	36
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	1,208
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	1,127	1,106
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	42
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	34
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 1,051
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	3.25%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	4.17%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	4.34%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	3.18%
Collateralized loan obligations [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 28,747	29,926
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	30
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	15,092
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	13,625
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	28,585	29,200
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	31
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	15,051
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 13,503
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	6.99%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	7.28%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	7.09%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	6.88%
Other debt securities [Member]
Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling Maturity [Abstract]
Held-to-maturity, amortized cost, net	$ 1,726	1,727
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	1,726
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	0
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	1,591	$ 1,578
Held-to-maturity, fair value, remaining contractual maturity, due within one year	0
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	1,591
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	0
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 0
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	4.47%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	0.00%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	4.47%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	0.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	0.00%