Results of Operations and Average Assets by Segment (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Branch Banking	Jun. 30, 2014 Branch Banking
Segment Reporting Information [Line Items]
Bank Premises Impairment	$ (18)	$ (1)	$ 18	$ 18