Schedule II-Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance For Loss On Receivables
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 137	$ 118	$ 94
Acquired Balances	(39)	0	0
Charged (Credited) to Costs and Expenses	61	32	37
Charged to Other Accounts	(7)	28	18
Deductions or Write-offs	(51)	(41)	(31)
Balance at End of Period	101	137	118
Deferred Tax Asset Valuation Allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	48	28	28
Acquired Balances	0	0	0
Charged (Credited) to Costs and Expenses	6	(20)	0
Charged to Other Accounts	0	0	0
Deductions or Write-offs	0	0	0
Balance at End of Period	$ 42	$ 48	$ 28