Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Tax benefits (costs) from share-based compensation	$ 34	$ 89	$ 66
Tax credits included in provision for income taxes	4	4	3
Tax provision (benefit) applicable to other comprehensive income	2	5	2
Cumulative unremitted earnings of subsidiaries	1,109
Change in unrecognized tax benefits	(14)	24	(5)
Unrecognized tax benefits that, if recognized, would impact the effective tax rate	15	7	12
Tax credits subject to expiration	34
Tax credits not subject to expiration	77
Net operating loss benefits	5	10
Net operating losses	961
Net operating losses subject to expiration	413
Net cash payments (receipts) for income tax (refunds)	218	$ 172	$ 77
International Issue Relating to Financing Activity and US Federal Tax Issue
Income Taxes [Line Items]
Change in unrecognized tax benefits, amount of unrecorded benefit	$ 15