Assets and Liabilities Measured at Fair Value on a Recurring Basis (Additional Information) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Cumulative effect of credit risk adjustment		$ 0
Government Guarantee Percent		2.00%
Derivative Assets	[1]	$ 1,735	$ 1,152
Derivative Liabilities	[2]	654	464
Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Investments, Fair Value Disclosure		47	93
Federal Reserve Bank Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investments, Fair Value Disclosure		402	402
Investment in Federal Home Loan Bank Stock [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investments, Fair Value Disclosure		64	32
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investments, Fair Value Disclosure		5	$ 6
AOCI Attributable to Parent [Member]
Cumulative effect of credit risk adjustment	[3]	$ (5)

[1] At March 31, 2016, $1.7 billion, net of $607 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2015, $1.2 billion, net of $397 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets.

[2] At March 31, 2016, $654 million, net of $1.3 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2015, $464 million, net of $1.0 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.

[3] Related to the Company's early adoption of the ASU 2016-01 provision related to changes in instrument-specific credit risk, for the three months ended March 31, 2016. See Note 1, "Significant Accounting Policies," and Note 17, "Accumulated Other Comprehensive Income/(Loss)," for additional information.