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, 2017	$ 1,241,996	$ 458	$ 1,063,974	$ 177,149	$ 415
Balance (in shares) at Dec. 31, 2017		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
Issuance of restricted stock, net (in shares)		198,627
Restricted stock surrendered and canceled	(1,579)		(1,579)
Restricted stock surrendered and canceled (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
Balance at Mar. 31, 2018	1,261,908	$ 472	1,065,218	205,069	(8,851)
Balance (in shares) at Mar. 31, 2018		46,527,566
Increase (Decrease) in Stockholders' Equity
Net income	27,303			27,303
Other comprehensive income	(3,362)				(3,362)
Share-based compensation expense	2,205		2,205
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)		1,205
Restricted stock surrendered and canceled	(41)		(41)
Restricted stock surrendered and canceled (in shares)		(2,681)
Exercise of stock options	512	$ (13)	525
Exercise of stock options (in shares)		103,028
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
Balance at Dec. 31, 2018	$ 1,969,697	$ 617	1,674,274	300,407	(5,601)
Balance (in shares) at Dec. 31, 2018	62,480,755	62,480,755
Increase (Decrease) in Stockholders' Equity
Net income	$ 38,718
Other comprehensive income	10,661
Balance at Mar. 31, 2019	2,007,064	$ 617	1,676,024	325,363	5,060
Balance (in shares) at Mar. 31, 2019		62,773,299
Balance at Dec. 31, 2018	$ 1,969,697	$ 617	1,674,274	300,407	(5,601)
Balance (in shares) at Dec. 31, 2018	62,480,755	62,480,755
Increase (Decrease) in Stockholders' Equity
Net income	$ 77,245			77,245
Other comprehensive income	27,959				27,959
Repurchase and retirement of common stock	(65,969)	$ (22)	(59,253)	(6,694)
Repurchase and retirement of common stock (in shares)		(2,219,246)
Cash dividends declared ($0.22 per common share)	(27,541)			(27,541)
Dividend equivalents declared ($0.22 per restricted stock units)	0		51	(51)
Share-based compensation expense	5,313		5,313
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)		304,754
Restricted stock surrendered and canceled	(2,629)		(2,629)
Restricted stock surrendered and canceled (in shares)		(99,206)
Exercise of stock options	381		381
Exercise of stock options (in shares)		42,937
Balance at Jun. 30, 2019	$ 1,984,456	$ 595	1,618,137	343,366	22,358
Balance (in shares) at Jun. 30, 2019	60,509,994	60,509,994
Balance at Mar. 31, 2019	$ 2,007,064	$ 617	1,676,024	325,363	5,060
Balance (in shares) at Mar. 31, 2019		62,773,299
Increase (Decrease) in Stockholders' Equity
Net income	38,527			38,527
Other comprehensive income	17,298				17,298
Repurchase and retirement of common stock	(65,969)	$ (22)	(59,253)	(6,694)
Repurchase and retirement of common stock (in shares)		(2,219,246)
Cash dividends declared ($0.22 per common share)	(13,792)			(13,792)
Dividend equivalents declared ($0.22 per restricted stock units)	0		38	(38)
Share-based compensation expense	2,860		2,860
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)		15,000
Restricted stock surrendered and canceled	(1,582)		(1,582)
Restricted stock surrendered and canceled (in shares)		(61,927)
Exercise of stock options	50		50
Exercise of stock options (in shares)		2,868
Balance at Jun. 30, 2019	$ 1,984,456	$ 595	$ 1,618,137	$ 343,366	$ 22,358
Balance (in shares) at Jun. 30, 2019	60,509,994	60,509,994