HTM Debt Securities, Contractual Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
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	$ 243,151	$ 262,708
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	189
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	1,578
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	17,163
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	224,221
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	211,716	227,316
Held-to-maturity, fair value, remaining contractual maturity, due within one year	187
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	1,550
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	17,210
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 192,769
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.75%
Held-to-maturity, weighted average yield, remaining contractual maturity, due within one year	1.18%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	4.19%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	6.76%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.43%
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	$ 3,793	3,790
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	3,793
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	2,261	2,287
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	$ 2,261
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	1.59%
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	1.59%
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	$ 18,320	18,624
Held-to-maturity, amortized cost, net, remaining contractual maturity, due within one year	189
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after one year through five years	459
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	556
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	17,116
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	15,509	15,688
Held-to-maturity, fair value, remaining contractual maturity, due within one year	187
Held-to-maturity, fair value, remaining contractual maturity, due after one year through five years	448
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	544
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 14,330
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	1.18%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after one year through five years	2.19%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	2.85%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	2.38%
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	$ 197,723	209,170
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	197,723
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	170,612	178,388
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	$ 170,612
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	2.35%
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	2.35%
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	$ 1,285	1,276
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	41
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	32
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	1,212
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	1,257	1,174
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	47
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	33
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 1,177
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	3.38%
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	5.57%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	4.37%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	3.27%
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	$ 20,303	28,122
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	102
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	15,824
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after ten years	4,377
Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value, Rolling Maturity [Abstract]
Held-to-maturity, fair value	20,375	28,134
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	102
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	15,884
Held-to-maturity, fair value, remaining contractual maturity, due after ten years	$ 4,389
Debt Securities, Held-to-Maturity, Rolling Maturity, Weighted Average Yield [Abstract]
Held-to-maturity weighted average yield	6.95%
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	7.13%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	7.00%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	6.76%
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	$ 1,727	1,726
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	976
Held-to-maturity, amortized cost, net, remaining contractual maturity, due after five years through ten years	751
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	1,702	$ 1,645
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	953
Held-to-maturity, fair value, remaining contractual maturity, due after five years through ten years	749
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	4.70%
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	4.75%
Held-to-maturity, weighted average yield, remaining contractual maturity, due after five years through ten years	4.63%
Held-to-maturity, weighed average yield, remaining contractual maturity, due after ten years	0.00%