Investments in Unconsolidated Affiliates (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	$ 413.5		$ 321.4
Symetra
Investments in unconsolidated affiliates
Equity in Unrealized Gains (Losses) from Investments in Unconsolidated Affiliates	20.5		(43.6)
Total investments in unconsolidated affiliates	409.8	415.5	317.3	325.2	326.0	381.5
Symetra | Common shareholders' equity.
Investments in unconsolidated affiliates
Symetra Common Shares excluding unrealized gains (losses)	389.3		360.9
Total investments in unconsolidated affiliates	409.8	415.5	317.3	325.2	326.0	351.2
Symetra | Warrants
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	0	0	0	0	0	30.3
Hamer, LLC
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	$ 3.7		$ 4.1