Statutory Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statutory Accounting Practices [Line Items]
Statutory risk-based capital necessary to satisfy regulatory requirements	$ 3,500.0				$ 3,400.0				$ 3,500.0	$ 3,400.0
GAAP equity	24,765.2				23,802.7				24,765.2	23,802.7	23,288.2	23,812.6
Net income	148.2	656.2	800.1	885.2	464.2	691.2	643.6	856.5	2,489.7	2,655.5	2,646.7
California Department of Managed Health Care [Member]
Statutory Accounting Practices [Line Items]
Statutory risk-based capital necessary to satisfy regulatory requirements	450.0				450.0				450.0	450.0
Insurance And HMO Subsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory-basis capital and surplus	10,003.0				9,967.7				10,003.0	9,967.7
Statutory-basis net income									2,594.8	2,800.0	2,402.5
DHMC Regulated Entities [Member]
Statutory Accounting Practices [Line Items]
GAAP equity	1,449.2				1,312.5				1,449.2	1,312.5
Net income									$ 487.7	$ 469.7	$ 524.3