Other Reinsurance Assumed Insurance (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assumed Insurance [Line Items]
Assumed Premiums Earned	$ 57.1	$ 52.7	$ 44.0
Capitol [Member]
Assumed Insurance [Line Items]
Number of Company Employee Board Members	5
Number of Board of Director Members	5
ORCC [Member]
Assumed Insurance [Line Items]
Number of Company Employee Board Members	9
Number of Board of Director Members	9
Capitol [Member]
Assumed Insurance [Line Items]
Assumed Premiums Earned	21.9	22.4	25.0
Capitol [Member] | Trinity [Member]
Assumed Insurance [Line Items]
Earned Premiums Assumed, Percentage	100.00%
ORCC [Member]
Assumed Insurance [Line Items]
Assumed Premiums Earned	6.7	7.2	8.2
ORCC [Member] | Trinity [Member]
Assumed Insurance [Line Items]
Earned Premiums Assumed, Percentage	100.00%
Non-Catastrophe Reinsurance [Member]
Assumed Insurance [Line Items]
Assumed Premiums Earned	$ 57.1	$ 52.7	$ 44.0