Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions			3 Months Ended
	Jan. 01, 2020	Jan. 01, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Summary of Accounting and Financial Policies [Line Items]
Firm's revenues from contracts with clients subject to ASU 2014-09 as a percentage of firm's total non-interest revenues			55.00%	50.00%
Investment Banking revenues from contracts with clients subject to ASU 2014-09 as a percentage of firm's investment banking revenues			85.00%	90.00%
Investment management revenues from contracts with clients subject to ASU 2014-09 as a percentage of firm's investment management revenue			95.00%	95.00%
Cash and due from banks			$ 11,700		$ 12,570
Interest-bearing deposits with banks			93,790		120,980
Cash segregated for regulatory and other purposes			28,930		22,780
Receivable from customers and counterparties			72,630		50,900
Receivables from brokers, dealers and clearing organizations			48,300		23,710
Firm's receivables from contracts with clients			2,310		2,270
Payables to customers and counterparties			201,680		170,210
Payables to brokers, dealers and clearing organizations			11,500		4,610
Lease liabilities			2,289		$ 2,385
Maximum [Member]
Summary of Accounting and Financial Policies [Line Items]
Annual average revenues associated with known remaining performance obligations			$ 250
Accounting Standards Update 2016-02 [Member]
Summary of Accounting and Financial Policies [Line Items]
Lease liabilities		$ 1,770
New accounting standards impact on retained earnings		$ 12
Accounting Standards Update 2016-13 [Member]
Summary of Accounting and Financial Policies [Line Items]
New accounting standards impact on retained earnings	$ (638)
Accounting Standards Update 2016-13 [Member] | Maximum [Member]
Summary of Accounting and Financial Policies [Line Items]
Allowance for credit losses	848
Accounting Standards Update 2016-13 [Member] | Minimum [Member]
Summary of Accounting and Financial Policies [Line Items]
Allowance for credit losses	$ 169