Deposits and Borrowings - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Deposits And Borrowings [Line Items]
Interest-bearing deposits	$ 191,874	$ 180,467
Domestic time deposits	12,200	8,300
Domestic time deposits $100,000 or more	1,900	2,300
Foreign time deposits	843	977
Securitized debt obligations	16,166	11,624
Issuance of securitized debt obligations	5,100
Maturities of secured debt	500
Senior and subordinated notes	21,837	18,684
Fair value hedging losses	134	179
Repayments of Unsecured Debt	2,800
Advances from Federal Home Loan Banks	20,100	17,300
Sum of investment in Federal Reserve stock used as security with Federal Reserve	1,200	1,200
Other Assets
Deposits And Borrowings [Line Items]
Investment in FHLB stock	2,100	$ 2,000
Senior notes | Total unsecured senior debt
Deposits And Borrowings [Line Items]
Proceeds from issuance of unsecured debt	6,000
Senior notes | Floating unsecured senior debt
Deposits And Borrowings [Line Items]
Proceeds from issuance of unsecured debt	700
Senior notes | Fixed unsecured senior debt
Deposits And Borrowings [Line Items]
Proceeds from issuance of unsecured debt	$ 5,300