Reinsurance - Narrative (Details) - USD ($)			3 Months Ended	12 Months Ended
		Jul. 01, 2015	Sep. 30, 2015	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Effects of Reinsurance [Line Items]
Ceded premiums written, net of profit commission				$ 55,391,000		$ 119,634,000		$ 73,503,000
Premiums earned, ceded				102,848,000		108,255,000		$ 38,101,000
Profit commission receivable				$ 0		$ 91,500,000
Period of existing captive reinsurance agreement				10 years		10 years		10 years
Reinsurance recoverable on loss reserves related to captive agreements				$ 34,000,000		$ 45,000,000
Fair value of trust fund assets under our captive agreements				137,000,000		198,000,000
Quota Share Reinsurance Agreement, 2013
Effects of Reinsurance [Line Items]
Ceded premiums written, net of profit commission			$ 69,400,000	(11,355,000)	[1]	100,031,000		$ 49,672,000
Premiums earned, ceded			11,600,000	35,999,000	[1]	88,528,000		13,821,000
Reinsurance, ceding commission			$ 11,600,000	10,235,000	[1],[2]	37,833,000	[2]	10,408,000	[2]
Profit commission		$ 142,500,000		62,525,000	[1]	$ 89,133,000		$ 2,368,000
Quota Share Reinsurance Agreement, 2015
Effects of Reinsurance [Line Items]
Ceded premiums written, net of profit commission	[3]			52,588,000
Premiums earned, ceded	[3]			52,588,000
Reinsurance, ceding commission	[2]			20,582,000
Profit commission				$ 50,322,000
Contingent termination fee		$ 0
Threshold for private mortgage insurer eligibility requirements for termination election		90.00%
Quota share, percentage		30.00%
Ceding commission, percentage		20.00%
Loss ratio		60.00%

[1] The year ended December 31, 2015 includes the non-recurring impact of commuting our 2013 QSR Transaction. The commutation had no impact on ceded losses incurred.

[2] Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations.

[3] As of July 1, 2015, premiums are ceded on an earned and received basis as defined in our 2015 QSR Transaction.