SCHEDULE IV (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Assumed premiums earned	$ 33.8	$ 38.4	$ 34.5
Reinsurance ceded	(132.9)	(142.8)	(187.9)
Insurance policy income	2,601.1	2,556.0	2,629.7
Life insurance inforce
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct	27,048.1	25,807.0	25,029.0
Assumed	128.7	137.4	147.1
Ceded	(3,604.0)	(3,780.8)	(3,660.1)
Net insurance inforce	$ 23,572.8	$ 22,163.6	$ 21,516.0
Percentage of assumed to net	0.50%	0.60%	0.70%
Insurance policy income
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct premiums earned	$ 2,553.0	$ 2,524.3	$ 2,558.2
Assumed premiums earned	34.0	38.5	35.0
Reinsurance ceded	(123.9)	(133.6)	(176.7)
Insurance policy income	$ 2,463.1	$ 2,429.2	$ 2,416.5
Premiums, percentage of assumed to net	1.40%	1.60%	1.40%