Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 45.7	$ 75.1
Other comprehensive income (loss), before tax:
Unrealized gains/losses on securities	315.9	(169.5)
Other-than-temporary impairments	6.6	0.9
Pension and other post-employment benefit liability	(0.6)	(0.6)
Other comprehensive income (loss), before tax	321.9	(169.2)
Income tax benefit (expense) related to items of other comprehensive income (loss)	112.4	(58.2)
Other comprehensive income (loss), after tax	209.5	(111.0)
Comprehensive income (loss)	$ 255.2	$ (35.9)