Sales Inducements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Changes in Deferred Sales Inducement Activity:
Deferred asset, beginning of period	$ 60.9	$ 49.7
Sales inducements deferred	2.8	4.8
Amortization charged to income	(0.7)	(3.6)
Offsets to net unrealized investment gains or losses included in AOCI	1.3	(0.1)
Deferred asset, end of period	$ 64.3	$ 50.8