Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 11.4		$ 2.6		$ 5.6	$ (4.6)	$ (4.6)
Change in component during the year before reclassifications	(17.6)		21.4
Amounts reclassified from AOCI	(5.7)		(12.6)
Ending balance	(11.9)		11.4		5.6	(4.6)	(4.6)
Net unrealized investment gains | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1.3)	[1]	(7.4)	[1]
Change in component during the year before reclassifications	3.9	[1]	6.7	[1]
Amounts reclassified from AOCI	(0.6)	[1]	(0.6)	[1]
Ending balance	2.0	[1]	(1.3)	[1]
Non-credit portion of OTTI losses recognized in OCI [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	12.7	[1]	10.0	[1]
Change in component during the year before reclassifications	(21.5)	[1]	14.7	[1]
Amounts reclassified from AOCI	(5.1)	[1]	(12.0)	[1]
Ending balance	$ (13.9)	[1]	$ 12.7	[1]

[1] See Note 6 to these financial statements for additional information regarding offsets to net unrealized investment gains and losses which include policyholder dividend obligation, DAC and other actuarial offsets, and deferred income tax expense (benefit).