Supplemental Unaudited Quarterly Financial Information Consolidated Statements of Changes in Stockholders' Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									6 Months Ended	9 Months Ended	12 Months Ended										3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 COMMON STOCK:	Sep. 30, 2013 COMMON STOCK:	Jun. 30, 2013 COMMON STOCK:	Mar. 31, 2013 COMMON STOCK:	Dec. 31, 2012 COMMON STOCK:	Dec. 31, 2011 COMMON STOCK:	Dec. 31, 2010 COMMON STOCK:	Mar. 31, 2013 ADDITIONAL PAID-IN CAPITAL:	Jun. 30, 2013 ADDITIONAL PAID-IN CAPITAL:	Sep. 30, 2013 ADDITIONAL PAID-IN CAPITAL:	Dec. 31, 2013 ADDITIONAL PAID-IN CAPITAL:	Dec. 31, 2012 ADDITIONAL PAID-IN CAPITAL:	Dec. 31, 2011 ADDITIONAL PAID-IN CAPITAL:	Jun. 30, 2013 Retained Earnings (Accumulated Deficit)	Sep. 30, 2013 Retained Earnings (Accumulated Deficit)	Dec. 31, 2013 Retained Earnings (Accumulated Deficit)	Dec. 31, 2012 Retained Earnings (Accumulated Deficit)	Dec. 31, 2011 Retained Earnings (Accumulated Deficit)	Mar. 31, 2013 Retained Earnings (Accumulated Deficit)	Jun. 30, 2013 ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):	Sep. 30, 2013 ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):	Dec. 31, 2013 ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):	Dec. 31, 2012 ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):	Dec. 31, 2011 ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):	Mar. 31, 2013 ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 258.3	$ 263.3	$ 258.7	$ 295.1					$ 424.0	$ 295.1	$ 295.1	$ 295.1	$ 424.0	$ 428.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 802.2	$ 802.2	$ 802.2	$ 802.2	$ 802.2	$ 802.2	$ (521.0)	$ (521.0)	$ (521.0)	$ (383.3)	$ (363.3)	$ (541.4)	$ 11.4	$ 11.4	$ 11.4	$ 2.6	$ (12.9)	$ (4.6)
Capital contributions from parent												(45.0)	0	0								0	0	0	45.0	0	0
Other comprehensive income (loss), net of income taxes	(17.5)	10.2	0	(16.0)						(16.0)	(5.8)	(23.3)	8.8	15.5																				(16.0)	(5.8)	(23.3)	8.8	15.5
Net income (loss)	86.7	(15.2)	4.6	(20.4)	[1]	(2.5)	(80.6)	(32.1)	(22.5)	(15.8)	(31.0)	55.7	(137.7)	(20.0)														(15.8)	(31.0)	55.7	(137.7)	(20.0)
Change in stockholder’s equity				(36.4)						(31.8)	(36.8)
Balance, end of period	$ 372.5	$ 258.3	$ 263.3	$ 258.7		$ 295.1				$ 263.3	$ 258.3	$ 372.5	$ 295.1	$ 424.0	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 2.5	$ 802.2	$ 802.2	$ 802.2	$ 847.2	$ 802.2	$ 802.2	$ (536.8)	$ (552.0)	$ (465.3)	$ (521.0)	$ (383.3)	$ (541.4)	$ (4.6)	$ 5.6	$ (11.9)	$ 11.4	$ 2.6	$ (4.6)

[1] Results for the quarter ended March 31, 2013 include $3.2 million of income (loss) related to out of period adjustments. Such amounts are not material to any period presented.