Reinsurance (Details) - USD ($)		3 Months Ended		6 Months Ended
	Jul. 01, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Reinsurance Disclosures [Abstract]
Premiums earned - Direct		$ 263,566,000	$ 240,171,000	$ 518,953,000	$ 485,919,000
Premiums earned - Assumed		182,000	308,000	390,000	646,000
Premiums earned - Ceded		(32,292,000)	(26,971,000)	(66,546,000)	(55,769,000)
Net premiums earned		231,456,000	213,508,000	452,797,000	430,796,000
Losses incurred - Direct		54,863,000	95,710,000	147,295,000	183,746,000
Losses incurred - Assumed		339,000	198,000	440,000	766,000
Losses incurred - Ceded		(8,612,000)	(5,670,000)	(16,133,000)	(12,489,000)
Net losses incurred		46,590,000	90,238,000	131,602,000	172,023,000
Premiums Written and Earned [Abstract]
Ceded premiums written, net of profit commission		32,280,000	34,937,000	66,498,000	66,231,000
Premiums earned - Ceded		32,292,000	26,971,000	66,546,000	55,769,000
Losses incurred - Ceded		8,612,000	5,670,000	16,133,000	12,489,000
Reinsurance recoverable on loss reserves		45,215,000	53,456,000	$ 45,215,000	53,456,000	$ 44,487,000	$ 57,841,000
Period of existing captive reinsurance agreement				10 years
Reinsurance recoverable on loss reserves related to captive agreements		23,000,000		$ 23,000,000		34,000,000
Fair value of trust fund assets under captive agreements		109,000,000		109,000,000		137,000,000
Quota Share Reinsurance Agreement, 2013
Reinsurance Disclosures [Abstract]
Premiums earned - Ceded			(22,954,000)		(47,567,000)
Losses incurred - Ceded			(1,187,000)		(6,060,000)
Premiums Written and Earned [Abstract]
Ceded premiums written, net of profit commission			30,919,000		58,055,000
Premiums earned - Ceded			22,954,000		47,567,000
Losses incurred - Ceded			1,187,000		6,060,000
Ceding commissions			11,681,000		21,803,000
Profit commission			$ 27,483,000		$ 50,957,000
Quota Share Reinsurance Agreement, 2015
Reinsurance Disclosures [Abstract]
Premiums earned - Ceded		(29,961,000)		(61,627,000)
Losses incurred - Ceded		(6,070,000)		(14,583,000)
Effects of Reinsurance [Line Items]
Contingent termination fee	$ 0
Threshold for private mortgage insurer eligibility requirements for termination election (less than)	90.00%
Quota share for all policies covered	30.00%
Ceding commission, percentage	20.00%
Loss ratio threshold for profit commissions	60.00%
Premiums Written and Earned [Abstract]
Ceded premiums written, net of profit commission		29,961,000		61,627,000
Premiums earned - Ceded		29,961,000		61,627,000
Losses incurred - Ceded		6,070,000		14,583,000
Ceding commissions		11,946,000		23,522,000
Profit commission		29,767,000		55,982,000
Reinsurance recoverable on loss reserves		$ 22,000,000		$ 22,000,000		$ 11,000,000