Income Taxes - Statutory Federal Income Tax Expense, Effective Income Tax Expense, Rates (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Abstract]
Statutory Federal Income Tax Expense									$ (110.0)	$ (42.8)	$ (23.9)
Statutory Federal Income Tax Expense, Rate									35.00%	35.00%	35.00%
Tax-exempt Income and Dividends Received Deduction									10.6	13.9	17.7
Tax-exempt Income and Dividends Received Deduction, Rate									(3.40%)	(11.40%)	(26.00%)
State Income Taxes									(0.2)	(0.8)	(1.0)
State Income Taxes, Rate									0.10%	0.70%	1.50%
Other, Net									(0.3)	(0.9)	0.6
Other, Net, Rate									0.10%	0.70%	(1.00%)
Income Tax Expense	$ (26.6)	$ (33.4)	$ (13.9)	$ (26.0)	$ 4.3	$ (25.9)	$ 5.1	$ (14.1)	$ (99.9)	$ (30.6)	$ (6.6)
Effective Income Tax Expense, Rate									31.80%	25.00%	9.50%