Investing Activities Investment Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Debt securities											$ 162.5	$ 134.4	$ 122.2
Equity securities											1.2	0.4	0.3
Policy loans											3.2	2.9	3.1
Limited partnerships and other investments											4.5	1.8	2.2
Fair value investments											2.1	2.9	4.0
Total investment income											173.5	142.4	131.8
Less: Investment expenses											1.5	1.5	0.9
Net investment income	$ 44.1	$ 42.0	$ 40.0	$ 36.3	$ 34.0	$ 33.2	$ 82.0	$ 67.2	$ 126.1	$ 103.5	$ 172.0	$ 140.9	$ 130.9