Securities - Amortized Cost and Fair Value of Asset Backed Securities (Detail) - USD ($)		Mar. 31, 2022	Dec. 31, 2021
Securities available-for-sale:
Amortized Cost		$ 35,127,000,000	$ 35,356,000,000
Allowance for Credit Losses		0	(1,000,000)
Unrealized Gains		92,000,000	305,000,000
Unrealized Losses		(1,521,000,000)	(362,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)	[1]	33,698,000,000	35,298,000,000
Securities held-to-maturity:
Amortized Cost		4,805,000,000	5,204,000,000
Allowance for Credit Losses		(1,000,000)	(1,000,000)
Unrealized Gains		28,000,000	157,000,000
Unrealized Losses		(74,000,000)	(1,000,000)
Fair Value		4,758,000,000	5,359,000,000
U.S. Treasury
Securities available-for-sale:
Amortized Cost		9,271,000,000	9,490,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		58,000,000	144,000,000
Unrealized Losses		(161,000,000)	(72,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		9,168,000,000	9,562,000,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Securities available-for-sale:
Amortized Cost		7,410,000,000	7,365,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		15,000,000	114,000,000
Unrealized Losses		(461,000,000)	(115,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		6,964,000,000	7,364,000,000
Securities held-to-maturity:
Amortized Cost		688,000,000	684,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		1,000,000	21,000,000
Unrealized Losses		(5,000,000)	0
Fair Value		684,000,000	705,000,000
Collateralized Mortgage Obligations, Issued by U.S. Government Sponsored Enterprises
Securities available-for-sale:
Amortized Cost		1,701,000,000	1,787,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		0	8,000,000
Unrealized Losses		(152,000,000)	(48,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		1,549,000,000	1,747,000,000
Securities held-to-maturity:
Amortized Cost		503,000,000	492,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		13,000,000	26,000,000
Unrealized Losses		(7,000,000)	0
Fair Value		509,000,000	518,000,000
Direct Agency Obligations U S Government Sponsored Enterprises
Securities available-for-sale:
Amortized Cost		1,858,000,000	1,775,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		7,000,000	16,000,000
Unrealized Losses		(35,000,000)	(4,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		1,830,000,000	1,787,000,000
Mortgage-backed Securities, Issued or Guaranteed by US Government Agency
Securities available-for-sale:
Amortized Cost		8,427,000,000	8,489,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		6,000,000	7,000,000
Unrealized Losses		(438,000,000)	(66,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		7,995,000,000	8,430,000,000
Securities held-to-maturity:
Amortized Cost		1,004,000,000	1,104,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		1,000,000	24,000,000
Unrealized Losses		(19,000,000)	0
Fair Value		986,000,000	1,128,000,000
Collateralized Mortgage Obligations, Issued or Guaranteed by US Government Agency
Securities available-for-sale:
Amortized Cost		3,597,000,000	3,730,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		1,000,000	7,000,000
Unrealized Losses		(253,000,000)	(49,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		3,345,000,000	3,688,000,000
Securities held-to-maturity:
Amortized Cost		2,601,000,000	2,915,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		12,000,000	85,000,000
Unrealized Losses		(43,000,000)	(1,000,000)
Fair Value		2,570,000,000	2,999,000,000
Direct Agency Obligations, Issued or Guaranteed by US Government Agency
Securities available-for-sale:
Amortized Cost		264,000,000	282,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		3,000,000	6,000,000
Unrealized Losses		(3,000,000)	0
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		264,000,000	288,000,000
Home equity
Securities available-for-sale:
Amortized Cost		18,000,000	20,000,000
Allowance for Credit Losses		0	(1,000,000)
Unrealized Gains		0	0
Unrealized Losses		(1,000,000)	0
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		17,000,000	19,000,000
Other
Securities available-for-sale:
Amortized Cost		106,000,000	107,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		0	0
Unrealized Losses		(9,000,000)	(6,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		97,000,000	101,000,000
Foreign debt securities
Securities available-for-sale:
Amortized Cost		2,475,000,000	2,311,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		2,000,000	3,000,000
Unrealized Losses		(8,000,000)	(2,000,000)
Securities available-for-sale (includes amortized cost of $35.1 billion and $35.4 billion at March 31, 2022 and December 31, 2021, respectively, an allowance for credit losses of nil and $1 million at March 31, 2022 and December 31, 2021, respectively, and $3.4 billion and $2.4 billion pledged to creditors at March 31, 2022 and December 31, 2021, respectively)		2,469,000,000	2,312,000,000
Obligations of U.S. states and political subdivisions
Securities held-to-maturity:
Amortized Cost		8,000,000	8,000,000
Allowance for Credit Losses		0	0
Unrealized Gains		0	0
Unrealized Losses		0	0
Fair Value		8,000,000	8,000,000
Asset-backed securities collateralized by residential mortgages
Securities held-to-maturity:
Amortized Cost		1,000,000	1,000,000
Allowance for Credit Losses		(1,000,000)	(1,000,000)
Unrealized Gains		1,000,000	1,000,000
Unrealized Losses		0	0
Fair Value		$ 1,000,000	$ 1,000,000

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at March 31, 2022 and December 31, 2021. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. March 31, 2022December 31, 2021(in millions)AssetsLoans$128 $46 Other assets51 55 Total assets$179 $101 LiabilitiesInterest, taxes and other liabilities$31 $9 Total liabilities$31 $9