7. Investing Activities (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011 As restated and amended [Member]	Dec. 31, 2010 As restated and amended [Member]
Total other-than-temporary debt impairment losses	$ (5.0)	$ (9.7)	$ (20.9)
Portion of loss recognized in OCI	2.2	6.9	10.1
Net debt impairment losses recognized in earnings	(2.8)	(2.8)	(10.8)
Debt security impairments:
U.S. government and agency
State and political subdivision	(0.1)
Foreign government
Corporate		(0.4)	(0.8)
CMBS	(0.1)	(0.4)	(1.6)
RMBS	(1.9)	(1.5)	(4.7)
CDO/CLO	(0.4)	(0.4)	(3.6)
Other asset-backed	(0.3)	(0.1)	(0.1)
Net debt security impairments	(2.8)	(2.8)	(10.8)
Equity security impairments		(0.4)
Impairment losses	(2.8)	(3.2)	(10.8)
Debt security transaction gains	22.8	2.5	3.4
Debt security transaction losses	(0.7)	(0.7)	(4.1)
Limited partnerships and other investment gains		0.1	0.6
Limited partnerships and other investment losses	(0.3)	(0.1)	(0.8)
Net transaction gains	21.8	1.8	(0.9)
Derivative instruments	(49.0)	6.2	(22.8)
Embedded derivatives	11.2	(33.2)	12.2
Inter-company reinsurance derivatives	(3.5)	9.0	(1.7)
Assets valued at fair value			1.6
Net realized investment losses, excluding impairment losses	(19.5)	(16.2)	(11.6)
Net realized investment losses, including impairment losses	$ (22.3)	$ (19.4)	$ (22.4)