Medical Claims Payable ((Favorable) Unfavorable Developments By Changes In Key Assumptions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Medical Claims Payable [Abstract]
Assumed trend factors	$ (591.3)	$ (467.9)	$ (399.5)
Assumed completion factors	(259.1)	(332.3)	(142.4)
Total	$ (850.4)	$ (800.2)	$ (541.9)