Insurance Liabilities (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Change in unpaid disability and health claims
Balance at beginning of year, Unpaid disability and health claims	$ 1,006.9	$ 1,061.8	$ 1,025.6
Incurred:
Incurred: Current year	711.8	1,074.0	1,611.9
Incurred: Prior years	9.7	(10.8)	11.1
Total incurred	721.5	1,063.2	1,623.0
Payments:
Payments: Current year	446.3	820.8	1,269.4
Payments: Prior years	216.1	297.3	317.4
Total payments	662.4	1,118.1	1,586.8
Balance at end of year:
Total balance at end of year, Unpaid disability and health claims: Current year	265.5	253.2	342.5
Total balance at end of year, Unpaid disability and health claims: Prior years	800.5	753.7	719.3
Total balance at end of year, Unpaid disability and health claims	1,066.0	1,006.9	1,061.8
Supplemental information:
Claim adjustment expense liabilities	46.6	42.9	40.1
Reinsurance recoverables	$ 211.0	$ 177.7	$ 156.2