CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2016	$ 459,740	$ 274	$ 345,138	$ 117,049	$ (2,721)
Balance (in shares) at Dec. 31, 2016		27,798,283
Increase (Decrease) in Stockholders' Equity
Net income	23,697			23,697
Other comprehensive income	5,981				5,981
Share-based compensation expense	2,797		2,797
Issuance of restricted stock, net (in shares)		53,468
Common stock issued (in shares)		11,959,022
Common stock issued	464,982	$ 120	464,862
Repurchase of common stock	(1,077)		(1,077)
Repurchase of common stock (in shares)		0
Exercise of stock options	3,611	$ 2	3,609
Exercise of stock options (in shares)		237,985
Balance at Jun. 30, 2017	959,731	$ 396	815,329	140,746	3,260
Balance (in shares) at Jun. 30, 2017		40,048,758
Balance at Dec. 31, 2017	$ 1,241,996	$ 458	1,063,974	177,149	415
Balance (in shares) at Dec. 31, 2017	46,245,050	46,245,050
Increase (Decrease) in Stockholders' Equity
Net income	$ 55,305			55,305
Other comprehensive income	(12,710)				(12,710)
Share-based compensation expense	3,917		3,917
Issuance of restricted stock, net	0		0
Issuance of restricted stock, net (in shares)		198,627
Repurchase of common stock	(1,579)		(1,579)
Repurchase of common stock (in shares)		(28,849)
Exercise of stock options	1,596	$ 1	1,595
Exercise of stock options (in shares)		214,290
Reclassification of certain tax effects of the Tax Cuts and Jobs Act	0			(82)	82
Balance at Jun. 30, 2018	$ 1,288,525	$ 459	$ 1,067,907	$ 232,372	$ (12,213)
Balance (in shares) at Jun. 30, 2018	46,629,118	46,629,118