Deferred Policy Acquisition Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Deferred Policy Acquisition Costs:
Policy acquisition costs deferred	$ 16.0		$ 20.4		$ 49.6		$ 63.7
Costs amortized to expenses:
Recurring costs	(21.7)		(5.1)		(59.7)		(78.2)
Assumption unlocking	0		(1.2)		0		(1.2)
Realized investment gains (losses)	(0.5)		(18.0)		(3.1)		(13.2)
Offsets to net unrealized investment gains or losses included in AOCI (1)	1.6	[1]	5.8	[1]	45.5	[1]	(25.6)	[1]
Change in deferred policy acquisition costs	(4.6)		1.9		32.3		(54.5)
Deferred policy acquisition costs, beginning of period	463.1		432.7		426.2		489.1
Deferred policy acquisition costs, end of period	$ 458.5		$ 434.6		$ 458.5		$ 434.6

[1] An offset to DAC and accumulated other comprehensive income (“AOCI”) is recorded each period to the extent that, had unrealized holding gains or losses from securities classified as available-for-sale actually been realized, an adjustment to DAC amortized using gross profits or gross margins would result.