Variable Interest Entities (Narrative) (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Variable Interest Entity [Line Items]
Carrying amounts of assets	$ 5,200,000,000		$ 5,200,000,000		$ 5,600,000,000
Carrying amounts of liabilities	4,900,000,000		4,900,000,000		5,300,000,000
Number of variable interest entities consolidated	0	0	0	0
Net realized gains (losses) related to deconsolidation	$ 0	$ 1,000,000	$ 0	$ 1,000,000