Related Parties (Details) (FS&C [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Trinity [Member]
Related Party Transaction [Line Items]
Amount of assets being managed by FS&C	$ 85.0
Investment expenses	0.1	0.1
Pension Plans [Member] | Investment Management Services for Defined Benefit Plan [Member]
Related Party Transaction [Line Items]
Investment expenses	0.1	0.1
Assets under Management, Carrying Amount	$ 158.9