Agreements with Related Parties (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ING Group N.V. [Member]
Related Party Transaction [Line Items]
Net premiums earned	$ 1.9	$ 2.6	$ 3.4
Losses and loss expenses and life policy benefits	0.6	1.3	0.8
Unpaid losses and loss expenses	10.0	12.9
Atradius N.V. [Member]
Related Party Transaction [Line Items]
Net premiums written			80.3
Net premiums earned			75.7
Losses and loss expenses and life policy benefits			35.2
Acquisition costs			$ 28.5