Restrictions on Cash and Dividends - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Restricted Cash and Cash Equivalents Items [Line Items]
Banking Subsidiary Reserve Requirement	$ 1,800,000,000	$ 1,600,000,000
Subsidiary Deposit To FRB	1,000,000,000	942,000,000
Dividend Received From Nonbank Companies And Related Subsidiaries	1,100,000,000	859,000,000
BHC stress test threshold				50,000,000,000
Minimum Tier 1 Common Ratio	5.00%
Shares acquired for treasury	654,000,000	1,320,000,000	650,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock	297,000,000	1,034,000,000
April 28, 2014 ASR
Restricted Cash and Cash Equivalents Items [Line Items]
Shares acquired for treasury	150,000,000
July 21, 2014 ASR
Restricted Cash and Cash Equivalents Items [Line Items]
Shares acquired for treasury	225,000,000
October 20, 2014 ASR
Restricted Cash and Cash Equivalents Items [Line Items]
Shares acquired for treasury	180,000,000
CCAR authorization
Restricted Cash and Cash Equivalents Items [Line Items]
Common stock dividends restrictions	The potential increase in the quarterly common stock dividend to $0.13 per share
Stock Repurchase Authorization Amount	669,000,000
Series H Preferred Stock
Restricted Cash and Cash Equivalents Items [Line Items]
Proceeds from Issuance of Preferred Stock and Preference Stock		593,000,000
Series I Preferred Stock
Restricted Cash and Cash Equivalents Items [Line Items]
Proceeds from Issuance of Preferred Stock and Preference Stock		441,000,000
Series J Preferred Stock
Restricted Cash and Cash Equivalents Items [Line Items]
Proceeds from Issuance of Preferred Stock and Preference Stock	297,000,000
Series J Preferred Stock | CCAR authorization
Restricted Cash and Cash Equivalents Items [Line Items]
Issuance of preferred stock	$ 300,000,000