Segments (PTOI and Assets Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Revenue Reconciling Item [Line Items]
Income (loss) before income taxes	$ 81.0	$ 102.9	$ 247.8	$ 228.9
Total Assets	22,882.2	22,424.4	22,882.2	22,424.4	$ 22,710.6
Insurance Services [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Income (loss) before income taxes	77.4	93.6	227.0	197.4
Total Assets	8,035.7	8,079.0	8,035.7	8,079.0
Asset Management Segment [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Income (loss) before income taxes	19.0	20.8	62.9	59.2
Total Assets	14,106.3	13,775.6	14,106.3	13,775.6
Other Category [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Income (loss) before income taxes	(15.4)	(11.5)	(42.1)	(27.7)
Total Assets	$ 740.2	$ 569.8	$ 740.2	$ 569.8