Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets
Unpaid loss discount	$ 39,746	$ 44,886
Unearned premium adjustment	22,847	22,889
Compensation related	20,190	18,130
Intangibles	1,001	1,435
Total deferred tax assets	83,784	87,340
Deferred tax liabilities
Deferred acquisition costs	9,754	9,287
Unrealized gains on investments, net	9,797	13,933
Fixed assets	1,291	3,401
Basis differentials–investments	25,512	17,492
Intangibles	22,067	24,644
Other	5,107	3,486
Total deferred tax liabilities	73,528	72,243
Net deferred tax assets (liabilities)	$ 10,256	$ 15,097