Details of Intangible Assets Included in Other Long-Term Assets (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	10 years 5 months 24 days
Cost	$ 1,063	$ 1,095
Accumulated Amortization	456	402
Net	607	693
Customer contracts/relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	9 years 9 months 18 days
Cost	764	792
Accumulated Amortization	349	310
Net	415	482
Trade names and technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	13 years 2 months 12 days
Cost	198	200
Accumulated Amortization	54	40
Net	144	160
Provider contracts
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	15 years 1 month
Cost	51	51
Accumulated Amortization	19	23
Net	32	28
Noncompetes And Other
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	6 years 7 months
Cost	50	52
Accumulated Amortization	34	29
Net	$ 16	$ 23