Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 20.5	$ 62.0
Other comprehensive income (loss), before tax:
Unrealized gains/losses on securities	517.5	206.5
Other-than-temporary impairments	0.4	1.2
Pension and other post-employment benefit liability	(0.6)	(0.6)
Other comprehensive income (loss), before tax	517.3	207.1
Income tax expense (benefit) related to items of other comprehensive income (loss)	178.0	71.8
Other comprehensive income (loss), after tax	339.3	135.3
Comprehensive income (loss)	$ 359.8	$ 197.3