Collateralized Agreements and Financings - Assets pledged as collateral (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Collateralized Agreements And Financings [Abstract]
Trading assets owned pledged in connection with repurchase agreements, securities lending agreements and other secured financings to counterparties that had the right to deliver or repledge	$ 66,605	$ 47,371
Investments pledged to counterparties that Had the right to deliver or repledge	10,968	7,710
Trading assets owned pledged in connection with repurchase agreements, securities lending agreements and other secured financings to counterparties that did not have right to deliver or repledge	101,578	67,683
Investments pledged to counterparties that did not have the right to deliver or repledge	849	617
Loans pledged to counterparties that do not have the right to deliver or repledge	6,628	5,240
Other assets (substantially all real estate and cash) owned and pledged in connection with other secured financings to counterparties that did not have the right to deliver or repledge	$ 12,337	$ 8,037