Schedule II-Valuation and Qualifying Accounts (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Valuation Allowances and Reserves [Roll Forward]
Charged (Credited) to Costs and Expenses	$ (32)	$ (37)	$ (26)
Allowance For Loss On Receivables
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	118	94	85
Acquired Balances	0	0	0
Charged (Credited) to Costs and Expenses	32	37	26
Charged to Other Accounts	28	18	8
Deductions or Write-offs	(41)	(31)	(25)
Balance at End of Period	137	118	94
Deferred Tax Asset Valuation Allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	(28)	(28)	(28)
Acquired Balances	0	0	0
Charged (Credited) to Costs and Expenses	(20)	0	0
Charged to Other Accounts	0	0	0
Deductions or Write-offs	0	0	0
Balance at End of Period	$ (48)	$ (28)	$ (28)