Reinsurance - Other Reinsurance Activity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Direct Business and Reinsurance:
Direct premiums	$ 22.3	$ 17.6	$ 42.1	$ 36.1
Premiums ceded to non-affiliate reinsurers	(17.2)	(15.9)	(33.9)	(33.7)
Premiums	5.1	1.7	8.2	2.4
Direct policy benefits incurred	42.3	79.2	97.4	139.4
Policy benefits assumed from non-affiliate reinsureds	0	1.5	0	1.5
Policy benefits ceded to:
Affiliate reinsurers	(9.0)	(0.4)	(9.0)	(2.3)
Non-affiliate reinsurers	(14.4)	(40.2)	(34.0)	(73.7)
Policy benefits ceded to reinsurers	(23.4)	(40.6)	(43.0)	(76.0)
Premiums paid to:
Affiliate reinsurers	5.8	5.1	11.1	9.5
Non-affiliate reinsurers	7.8	9.7	10.7	23.7
Premiums paid to reinsurers	13.6	14.8	21.8	33.2
Policy benefits	32.5	54.9	76.2	98.1
Interest credited to policyholders and other items	$ 58.9	$ 36.7	$ 103.7	$ 55.3