Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 139
Balance at End of Year	119	$ 139
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	46	81	$ 68
Charged to Costs and Expenses	22	10	16
Valuation Allowances and Reserves, Reserves of Businesses Acquired	0	0	31
Deductions	(29)	(45)	(34)
Balance at End of Year	$ 39	$ 46	$ 81