Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Net premiums written	$ 370,568	$ 276,778	$ 186,200
Increase in unearned premiums	(44,097)	(53,549)	(62,829)
Net premiums earned	326,471	223,229	123,371
Net investment income	19,885	12,285	4,110
Realized investment gains, net	2,554	925	116
Other income	4,380	3,028	3,806
Total revenues	353,290	239,467	131,403
Losses and expenses:
Provision for losses and LAE	11,905	6,308	2,321
Other underwriting and operating expenses	112,987	97,232	71,055
Total losses and expenses	124,892	103,540	73,376
Income before income taxes	228,398	135,927	58,027
Total income tax expense (benefit)	71,067	47,430	(7,386)
Net income	$ 157,331	$ 88,497	$ 65,413
Earnings per share:
Basic (in dollars per share)	$ 1.74	$ 1.05	$ 0.90
Diluted (in dollars per share)	$ 1.72	$ 1.03	$ 0.70
Weighted average common shares outstanding:
Basic (in shares)	90,351	83,986	14,044
Diluted (in shares)	91,738	85,602	18,103
Other comprehensive income (loss):
Net income	$ 157,331	$ 88,497	$ 65,413
Other comprehensive income (loss):
Change in unrealized appreciation (depreciation) of investments, net of tax expense (benefit) of ($1,285) in 2015, $2,825 in 2014 and ($2,080) in 2013	(4,766)	6,114	(3,861)
Total other comprehensive income (loss)	(4,766)	6,114	(3,861)
Comprehensive income	$ 152,565	$ 94,611	$ 61,552