Reinsurance (Details) (USD $) In Thousands, 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
Premiums Written [Abstract]
Direct									$ 314,784	$ 284,200	$ 274,101
Ceded on direct									(112,967)	(105,292)	(84,130)
Net direct									201,817	178,908	189,971
Assumed									54,692	57,086	60,425
Ceded on assumed									(2,825)	(2,316)	(1,913)
Net assumed									51,867	54,770	58,512
Net									253,684	233,678	248,483
Premium Earned [Abstract]
Direct									313,842	287,982	270,002
Ceded on direct									(111,057)	(101,396)	(83,580)
Net direct									202,785	186,586	186,422
Assumed									52,783	53,191	60,061
Ceded on assumed									(2,825)	(2,316)	(1,913)
Net assumed									49,958	50,875	58,148
Net	65,422	64,448	61,775	61,098	61,402	54,853	59,655	61,551	252,743	237,461	244,570
Net losses and loss expenses incurred reduced by ceded reinsurance recoveries									107,321	90,899	56,600
Net losses and loss expense incurred from reinsurance assumed from non-affiliates									20,014	16,486	88,934
Retrocessional recoveries										20,000
Components of reinsurance recoverable [Abstract]
Case unpaid losses, net of valuation allowance	133,484				105,940				133,484	105,940
Incurred but not reported unpaid losses and loss expenses	52,157				59,421				52,157	59,421
Paid losses and loss expenses	4,126				2,506				4,126	2,506
Unearned premiums	5,801				7,324				5,801	7,324
Reinsurance recoverable	195,568				175,191				195,568	175,191
Reinsurance Receivables, Incurred but Not Reported Claims	$ 52,157				$ 59,421				$ 52,157	$ 59,421