Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013		Dec. 31, 2013
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Income (loss) before income taxes	$ 103.0	$ 112.8	$ 164.7	$ 219.7
Tax rate	35.00%	35.00%	35.00%	35.00%
Income tax expense (benefit) at federal statutory rate	36.1	39.5	57.6	76.9
Dividends received deduction	(7.9)	(6.3)	(13.9)	(11.6)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	0	1.9	0	1.9
IRS audit adjustment	0	0	(0.1)	(0.3)
Other	0.2	0.8	0.8	0.8	[1]
Income tax expense (benefit)	28.4	35.9	44.4	67.7
Increase (decrease) in valuation allowance		0
Foreign tax credits
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Valuation allowance, deferred tax assets	11.1		11.1
Tax valuation allowance allocated to Net income (loss)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Valuation allowance, deferred tax assets	130.4		130.4			130.4
Increase (decrease) in valuation allowance	0	1.9	0	1.9
Tax valuation allowance allocated to Other comprehensive income
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Valuation allowance, deferred tax assets	(119.3)		(119.3)			(119.3)
Increase (decrease) in valuation allowance	0	(1.9)	0	(1.9)
Operating loss carryforwards | Foreign tax credits
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Valuation allowance, deferred tax assets						$ 11.1

[1] Less than $0.1.