Details of Intangible Assets Included in Other Long-Term Assets (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	10 years 4 months 24 days
Cost	$ 1,016	$ 1,025
Accumulated Amortization	341	294
Net	675	731
Customer contracts/relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	9 years 6 months
Cost	725	733
Accumulated Amortization	267	237
Net	458	496
Trade names and technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	13 years 7 months 6 days
Cost	189	190
Accumulated Amortization	30	21
Net	159	169
Provider contracts
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	15 years
Cost	51	51
Accumulated Amortization	21	19
Net	30	32
Noncompetes And Other
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	6 years 6 months
Cost	51	51
Accumulated Amortization	23	17
Net	$ 28	$ 34