Financing Agreements - Narrative (Details) (USD $)	3 Months Ended		0 Months Ended	12 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Feb. 14, 2014 Revolving Credit agreement	Dec. 31, 2013 Revolving Credit agreement	Mar. 31, 2014 Revolving Credit agreement	Mar. 31, 2014 Letter of Credit	Jan. 24, 2014 Letter of Credit	Mar. 31, 2014 ING Bank	Mar. 31, 2014 Lion Connecticut Holdings Debentures Aetna Notes	Mar. 31, 2014 Lion Connecticut Holdings Debentures Aetna Notes Minimum	Mar. 31, 2014 Lion Connecticut Holdings Debentures Aetna Notes Maximum	Jan. 15, 2014 Trust Notes	Jan. 02, 2014 Trust Notes
Debt Instrument [Line Items]
Fees paid for guarantee								0.10%
Basis spread			1.75%	2.00%
Minimum principal outstanding in year two									$ 400,000,000
Minimum principal outstanding in year three									300,000,000
Minimum principal outstanding in year four									200,000,000
Minimum principal outstanding in year five									100,000,000
Minimum principal outstanding in year six									0
Quarterly fee to guarantor of notes if minimum principal balance is not met										0.50%	1.25%
Outstanding par amount of guaranteed debentures	506,100,000
Revolving lines of credit	9,977,900,000		3,000,000,000	3,500,000,000			150,000,000	1,275,000,000				500,000,000	565,000,000
Credit facility, sublimit, maximum borrowing capacity			750,000,000
Outstanding borrowings	5,599,900,000				0	829,900,000		673,100,000
Payments of financing costs	$ 29,300,000	$ 45,400,000	$ 700,000