Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Increase (Decrease) in deferred tax assets	$ (81)	$ (30)	$ 129