Variable Interest Entities - Consolidated Variable Interest Entities (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Assets
Cash and cash equivalents	$ 240,289		$ 155,842	$ 132,599	$ 133,546
Trading assets	375,917		393,630
Investments	90,727		88,445
Loans	130,537		116,115
Other assets	37,981		37,445
Total assets	1,387,922	$ 1,301,548	1,163,028
Liabilities
Other secured financings	27,633		25,755
Customer and other payables	238,697		190,658
Trading liabilities	199,093		153,727
Unsecured short-term borrowings	61,740		52,870
Unsecured long-term borrowings	238,930		213,481
Other liabilities	23,948		22,451
Total liabilities	1,286,032	$ 1,203,884	1,067,096
Real Estate, Credit-Related and Other Investing [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	129		229
Trading assets	38		8
Investments	867		880
Loans	1,738		2,099
Other assets	575		989
Total assets	3,347		4,205
Liabilities
Other secured financings	312		649
Customer and other payables	5		28
Trading liabilities	54		46
Other liabilities	946		948
Total liabilities	1,317		1,671
Corporate Debt and Other Asset-Backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	86		83
Total assets	86		83
Liabilities
Other secured financings	627		679
Total liabilities	627		679
Principal-Protected Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Trading assets	117		88
Total assets	117		88
Liabilities
Other secured financings	409		563
Trading liabilities			250
Unsecured short-term borrowings	40		43
Unsecured long-term borrowings	207		226
Total liabilities	656		1,082
Consolidated Variable Interest Entity, Total Carrying Amount [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	215		312
Trading assets	155		96
Investments	867		880
Loans	1,738		2,099
Other assets	575		989
Total assets	3,550		4,376
Liabilities
Other secured financings	1,348		1,891
Customer and other payables	5		28
Trading liabilities	54		296
Unsecured short-term borrowings	40		43
Unsecured long-term borrowings	207		226
Other liabilities	946		948
Total liabilities	$ 2,600		$ 3,432