Investments - Mortgage Loans (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Maximum loan to value ratio generally allowed	75.00%
Commercial mortgage loans	$ 3,378,200,000	[1]	$ 3,397,300,000	[1]
Collective valuation allowance	(1,200,000)		(1,200,000)
Total net commercial mortgage loans	3,377,000,000		3,396,100,000
Impairments on mortgage loans	$ 0

[1] Balances do not include allowance for mortgage loan credit losses.