Commitments And Contingencies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) class_actions
Commitments And Contingencies [Line Items]
California gross premium tax rate	2.35%
Possible losses, in excess of established reserves, minimum	$ 0.0
Possible losses, in excess of established reserves, maximum	250.0
Accenture LLP [Member]
Commitments And Contingencies [Line Items]
Long-term purchase commitment, amount	224.0
Affiliated Computer Services, Inc. [Member]
Commitments And Contingencies [Line Items]
Long-term purchase commitment, amount	15.7
International Business Machines Corporation [Member]
Commitments And Contingencies [Line Items]
Long-term purchase commitment, amount	$ 378.4
In re WellPoint, Inc. (n/k/a Anthem, Inc.) Out-of-Network UCR Rates Litigation [Member]
Commitments And Contingencies [Line Items]
Number of putative class actions consolidated into a single lawsuit | class_actions	11