Schedule II-Financial Information of Registrant (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments available for sale, at fair value
Fixed maturities	$ 1,190,638	$ 846,925
Short-term investments	85,996	210,688
Total investments	1,276,634	1,057,613
Cash	24,606	24,411
Other assets	3,492	2,768
Total assets	1,469,099	1,181,461
Liabilities
Other accrued liabilities	12,138	8,444
Total liabilities	$ 349,858	$ 225,723
Commitments and contingencies
Stockholders' Equity
Common shares	$ 1,390	$ 1,388
Additional paid-in capital	904,221	893,285
Accumulated other comprehensive income (loss)	(99)	4,667	$ (1,447)
Retained earnings	213,729	56,398
Total stockholders' equity	1,119,241	955,738	$ 722,141	$ 219,123
Total liabilities and stockholders' equity	1,469,099	1,181,461
Parent Company
Investments available for sale, at fair value
Fixed maturities	36,549	1,197
Short-term investments	25,511	116,630
Total investments	62,060	117,827
Cash	8,541	8,500
Due from affiliates	1,021	1,179
Investment in consolidated subsidiaries	1,047,114	828,482
Other assets	866	668
Total assets	1,119,602	956,656
Liabilities
Other accrued liabilities	361	918
Total liabilities	$ 361	$ 918
Commitments and contingencies
Stockholders' Equity
Common shares	$ 1,390	$ 1,388
Additional paid-in capital	904,221	893,285
Accumulated other comprehensive income (loss)	(99)	4,667
Retained earnings	213,729	56,398
Total stockholders' equity	1,119,241	955,738
Total liabilities and stockholders' equity	$ 1,119,602	$ 956,656