General (Details) (USD $)	3 Months Ended
	Mar. 31, 2015 segment	Mar. 31, 2014
Operating results by business segment
Number of segments	5
Revenues	$ 980,968,000	$ 966,475,000
Commercial | Risk Based Product
Operating results by business segment
Covered Lives	2,700,000
Revenues	69,700,000
Commercial | ASO (Administrative Services Only)
Operating results by business segment
Covered Lives	15,100,000
Revenues	31,300,000
Commercial | EAP (Employee Assistance Programs)
Operating results by business segment
Covered Lives	13,400,000
Revenues	51,500,000
Public Sector | Risk Based Product
Operating results by business segment
Covered Lives	1,400,000
Revenues	407,800,000
Public Sector | ASO (Administrative Services Only)
Operating results by business segment
Covered Lives	1,800,000
Revenues	15,200,000
Specialty Solutions | Risk Based Product
Operating results by business segment
Covered Lives	7,200,000
Revenues	110,200,000
Specialty Solutions | ASO (Administrative Services Only)
Operating results by business segment
Covered Lives	15,000,000
Revenues	14,100,000
Pharmacy Management
Operating results by business segment
Number of multiple applied for adjusted claim	3
Number of days for applying the multiple	90 days
Number of states served	26
Pharmacy Management | PBM (Pharmacy Benefit Management)
Operating results by business segment
Adjusted claims paid	3,000,000
Pharmacy Management | PBA (Pharmacy Benefit Administration)
Operating results by business segment
Adjusted claims paid	14,800,000
Pharmacy Management | Specialty Dispensing
Operating results by business segment
Adjusted claims paid	$ 27,900
Pharmacy Management | Commercial PBM
Operating results by business segment
Generic dispensing rate (as a percent)	82.90%
Number of members served	900,000
Pharmacy Management | Medical pharmacy management programs
Operating results by business segment
Number of members served	10,500,000
Managed Healthcare
Operating results by business segment
Number of segments	2