Valuation And Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 34	$ 34	$ 50
Expensed	27	24	17
Other Adjustments	(2)	(3)	(3)
Deductions	21	21	30
Balance at End of Period	38	34	34
Tax Valuation Allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	351	319	347
Expensed	17	20	(9)
Other Adjustments	3	12	(13)
Deductions	14	0	6
Balance at End of Period	$ 357	$ 351	$ 319