Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	$ 95,261	$ 100,445
Loans held for sale	1,000	596
Derivative assets, gross amount	2,690	3,415
Derivative asset, netting adjustments	(542)	(1,148)
Derivative asset	2,148	2,267
Liabilities:
Derivative liabilities, gross amount	1,868	1,518
Derivative liability, netting adjustments	(544)	(739)
Derivative liability	1,324	779
Net valuation allowance	11	31
Level 1
Assets:
Loans held for sale	0	0
Level 2
Assets:
Loans held for sale	5,091	2,214
Level 3
Assets:
Loans held for sale	0	0
Recurring
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	95,261	100,445
Loans held for sale	1,026	596
Derivative asset	2,148	2,267
Other assets	573	1,037
Total assets	99,008	104,345
Liabilities:
Derivative liability	1,324	779
Recurring | Level 1
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9,648	9,460
Loans held for sale	0	0
Derivative assets, gross amount	406	268
Other assets	526	430
Total assets	10,580	10,158
Other assets:
Deferred compensation plan assets	490	414
Liabilities:
Derivative liabilities, gross amount	838	271
Recurring | Level 2
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	85,346	90,546
Loans held for sale	1,026	596
Derivative assets, gross amount	2,200	3,006
Other assets	6	552
Total assets	88,578	94,700
Liabilities:
Derivative liabilities, gross amount	965	1,137
Recurring | Level 3
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	267	439
Loans held for sale	0	0
Derivative assets, gross amount	84	141	$ 77
Other assets	41	55
Total assets	392	635
Other assets:
Retained interests in securitizations	41	55
Liabilities:
Derivative liabilities, gross amount	65	110	$ 51
Recurring | Fair Value Inputs Level 1 And Level 2 [Member]
Other assets:
Equity securities	42	568
Liabilities:
Debt and Equity Securities, Unrealized Gain (Loss)	(36)	535
U.S. Treasury securities
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9,442	9,318
U.S. Treasury securities | Recurring
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9,442	9,318
U.S. Treasury securities | Recurring | Level 1
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9,442	9,318
U.S. Treasury securities | Recurring | Level 2
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	0	0
U.S. Treasury securities | Recurring | Level 3
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	0	0
RMBS
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	73,616	76,703
RMBS | Recurring
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	73,616	76,703
RMBS | Recurring | Level 1
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	0	0
RMBS | Recurring | Level 2
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	73,358	76,375
RMBS | Recurring | Level 3
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	258	328
CMBS | Recurring
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9,369	11,735
CMBS | Recurring | Level 1
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	0	0
CMBS | Recurring | Level 2
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9,360	11,624
CMBS | Recurring | Level 3
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	9	111
Other securities
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	2,834	2,689
Other securities | Recurring
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	2,834	2,689
Other securities | Recurring | Level 1
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	206	142
Other securities | Recurring | Level 2
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	2,628	2,547
Other securities | Recurring | Level 3
Assets:
Securities available for sale (amortized cost of $94.9 billion and $97.6 billion and allowance for credit losses of $1 million as of both December 31, 2021 and 2020)	$ 0	$ 0