Business Segment Information - Changes Related to Allocation of Corporate Operational Support Functions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Summary of changes by business segment
Segment profit (loss) before Corporate allocations	$ 56,894	$ 53,167	$ 116,826	$ 118,114
Segment profit (loss)	56,894	53,167	116,826	118,114
Operating segments | Healthcare
Summary of changes by business segment
Segment profit (loss) before Corporate allocations	50,719	47,522	104,246	115,470
Allocated Corporate costs	(17,661)	(17,280)	(35,302)	(35,227)
Allocated Corporate stock compensation expense	1,364	1,290	2,688	3,489
Segment profit (loss)	34,422	31,532	71,632	83,732
Operating segments | Pharmacy Management
Summary of changes by business segment
Segment profit (loss) before Corporate allocations	36,256	30,960	68,963	55,465
Allocated Corporate costs	(4,325)	(4,608)	(8,866)	(9,293)
Allocated Corporate stock compensation expense	341	323	672	872
Segment profit (loss)	32,272	26,675	60,769	47,044
Corporate and Elimination
Summary of changes by business segment
Segment profit (loss) before Corporate allocations	(30,081)	(25,315)	(56,383)	(52,821)
Allocated Corporate costs	21,986	21,888	44,168	44,520
Allocated Corporate stock compensation expense	(1,705)	(1,613)	(3,360)	(4,361)
Segment profit (loss)	$ (9,800)	$ (5,040)	$ (15,575)	$ (12,662)