Fair Value Measurements (Narrative) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Net Assets Measured At Fair Value On A Recurring Basis	$ 2,500,000,000	$ 2,500,000,000
Net Assets Measured At Fair Value On A Recurring Basis Measured Using Unobservable Input And Classified As Level3	$ 37,000,000	$ 88,000,000