Insurance Liabilities (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in unpaid disability and health claims
Balance at beginning of year, Unpaid disability and health claims	$ 1,061.8	$ 1,025.6	$ 991.8
Incurred:
Incurred: Current year	1,074.0	1,611.9	1,888.3
Incurred: Prior years	(10.8)	11.1	(33.4)
Total incurred	1,063.2	1,623.0	1,854.9
Payments:
Payments: Current year	820.8	1,269.4	1,507.1
Payments: Prior years	297.3	317.4	314.0
Total payments	1,118.1	1,586.8	1,821.1
Balance at end of year:
Total balance at end of year, Unpaid disability and health claims: Current year	253.2	342.5	381.2
Total balance at end of year, Unpaid disability and health claims: Prior years	753.7	719.3	644.4
Total balance at end of year, Unpaid disability and health claims	1,006.9	1,061.8	1,025.6
Supplemental information:
Claim adjustment expense liabilities	42.9	42.7	40.7
Reinsurance recoverables	$ 1.1	$ 1.6	$ 3.7