Employee Benefit Plans - Stock Purchase Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined contribution plan
Recorded in share-based compensation, after the effects of DAC	$ 8.0	$ 7.0	$ 8.0
Stock Purchase Plan
Defined contribution plan
Proceeds from purchase of shares by employees	0.9	0.6	0.7
Number of shares issued by the Company	57,980	54,612	50,523
Recorded in share-based compensation, after the effects of DAC	$ 0.3	$ 0.2	$ 0.2