Assets and Liabilities Measured at Fair Value on a Recurring Basis (Additional Information) (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Government Guarantee Percent		2.00%
Derivative Assets	[1]	$ 1,152	$ 1,307
Derivative Liabilities	[2]	464	462
Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Investments, Fair Value Disclosure		93	138
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		32	376
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investments, Fair Value Disclosure		$ 6	$ 7

[1] 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. At December 31, 2014, $1.3 billion, net of $449 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets.

[2] 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. At December 31, 2014, $462 million, net of $1.0 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.