Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Unrealized gains (losses) on available-for-sale securities, tax portion		$ 3	$ 1
Foreign currency translation adjustments, income tax benefit	$ 35	87	25
Defined benefit plans, income tax expense (benefit)	(10)	13	11
Change in fair value of derivative instruments, income tax expense (benefit)	4	(8)	(14)
Defined benefit plans, Expense reclassified into operations from other comprehensive income, Income tax benefits	7	7	12
Change in fair value of derivative instruments, Expense reclassified into operations from other comprehensive income, Income tax benefits	7	$ 40	$ 46
Expense (income) reclassified into operations from other comprehensive income, net of tax	$ 1