Investments in Unconsolidated Affiliates (Details) (USD $) In Millions	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	$ 422.9		$ 389.7
Symetra
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	421.0	392.8	387.5	372.5	329.0	307.7
Symetra | Common shareholders' equity
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	388.5	356.9	350.4	344.9	290.5	269.2
Symetra | Warrants
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	32.5	35.9	37.1	27.6	38.5	38.5
Pentelia Capital Management
Investments in unconsolidated affiliates
Total investments in unconsolidated affiliates	$ 1.9		$ 2.2