Risk Rating Under the Risk Rating System (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Credit Risk Associated With Commitments To Extend Credit [Line Items]
Commitments to Extend Credit	$ 62,050	$ 53,403
Pass
Credit Risk Associated With Commitments To Extend Credit [Line Items]
Commitments to Extend Credit	61,364	52,812
Risk Level Special Mention [Member]
Credit Risk Associated With Commitments To Extend Credit [Line Items]
Commitments to Extend Credit	369	370
Risk Level, Substandard
Credit Risk Associated With Commitments To Extend Credit [Line Items]
Commitments to Extend Credit	316	221
Risk Level, Doubtful
Credit Risk Associated With Commitments To Extend Credit [Line Items]
Commitments to Extend Credit	$ 1