Income Tax Matters, Income Tax Benefit (Provision) Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Federal income tax (expense) benefit
Current federal tax (expense) benefit	$ 0.7	$ (1.0)	$ 1.1
Deferred federal income tax (expense) benefit	93.2	6.4	(49.7)
Federal benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	33.5	(41.6)	1.3
Federal income tax (expense) benefit	127.4	(36.2)	(47.3)
Foreign income tax (expense) benefit
Current foreign tax (expense) benefit	2.1	1.0	16.2
Deferred foreign income tax (expense) benefit	(1.2)	0.3	(0.5)
Foreign benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	0.4	(0.5)	(0.1)
Foreign income tax (expense) benefit	1.3	0.8	15.6
State income tax (expense) benefit
Current state tax (expense) benefit	0.4	(0.6)	(0.2)
Deferred state income tax (expense) benefit	1.8	5.1	(6.7)
State benefit (expense) applied to increase (decrease) additional capital/Other comprehensive income	4.3	(4.4)	0.2
State income tax (expense) benefit	6.5	0.1	(6.7)
Total income tax (expense) benefit
Current income tax (expense) benefit	3.2	(0.6)	17.1
Deferred income tax (expense) benefit	93.8	11.8	(56.9)
Benefit (expense) applied to increase (decrease) Additional capital/Other comprehensive income	38.2	(46.5)	1.4
Income tax benefit (provision)	$ 135.2	$ (35.3)	$ (38.4)