Summary of Significant Accounting Policies - Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net revenues
Managed Care Revenue	$ 2,700.0	$ 2,600.0	$ 2,700.0
Fee-For-Service and Cost-Plus Contracts Revenue	342.0	290.9	215.1
Rebate Revenues	88.7	43.6	34.8
PBM Revenue	1,200.0	575.7	106.7
Dispensing Revenue	$ 211.6	$ 216.0	$ 376.6