Supplemental Unaudited Quarterly Financial Information Summarized Selected Quarterly Financial Data (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 117.9	$ 130.0	$ 133.1	$ 96.7	$ 145.9	$ 128.0	$ 134.9	$ 110.0	$ 229.8	$ 244.9	$ 359.8	$ 372.9	$ 477.7	$ 518.8	$ 470.6
Benefits and expenses	202.4	137.0	131.5	112.3	53.4	141.0	147.3	137.4	243.8	284.7	380.8	425.7	583.2	479.1	592.7
Income tax expense (benefit)	10.4	(11.8)	5.6	(0.4)	(7.1)	1.2	(16.9)	(1.9)	5.2	(18.8)	(6.6)	(17.6)	3.8	(24.7)	17.0
Net income (loss)	(94.9)	4.8	(4.0)	(15.2)	99.6	(14.2)	4.5	(25.5)	(19.2)	(21.0)	(14.4)	(35.2)	(109.3)	64.4	(139.1)
Less: Net (income) loss attributable to noncontrolling interests	0	0	0	0	0	0	0	0
Net income (loss)	$ (94.9)	$ 4.8	$ (4.0)	$ (15.2)	$ 99.6	$ (14.2)	$ 4.5	$ (25.5)	$ (19.2)	$ (21.0)	$ (14.4)	$ (35.2)	$ (109.3)	$ 64.4	$ (139.1)