Loans Receivable - Lending Commitments Held for Investments and Accounted for on Accrual Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Loans Receivable [Line Items]
Lending commitments held for investment	$ 139,060	$ 120,997
Corporate Loans [Member]
Loans Receivable [Line Items]
Lending commitments held for investment	120,777	113,484
Credit card [Member]
Loans Receivable [Line Items]
Lending commitments held for investment	9,596
Other Loans [Member]
Loans Receivable [Line Items]
Lending commitments held for investment	$ 8,687	$ 7,513