Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (shares) at Dec. 31, 2017		68,791	25,987
Beginning balance at Dec. 31, 2017	$ 185,865	$ 95	$ (334,312)	$ 373,045	$ 190,431	$ (43,394)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	5,735			5,735
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units (shares)		1,095	38
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units	(208)	$ 1	$ 226	(435)
Repurchases of common stock (shares)		(1,777)	(1,777)
Repurchases of common stock	(25,946)		$ (25,946)
Series A convertible preferred stock dividends	(6,000)				(6,000)
Series A convertible preferred stock accretion	(1,882)				(1,882)
Net income	50,831				50,831
Other comprehensive income (loss)	(11,395)					(11,395)
Other	1,226			1,226
Ending balance (shares) at Jun. 30, 2018		68,109	27,802
Ending balance at Jun. 30, 2018	198,226	$ 96	$ (360,032)	379,571	233,380	(54,789)
Beginning balance (shares) at Mar. 31, 2018		68,277	27,446
Beginning balance at Mar. 31, 2018	183,484	$ 96	$ (355,209)	376,808	202,954	(41,165)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,341			3,341
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units (shares)		210	(22)
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units	484	$ 0	$ 1,062	(578)
Repurchases of common stock (shares)		(378)	(378)
Repurchases of common stock	(5,885)		$ (5,885)
Series A convertible preferred stock dividends	(3,000)				(3,000)
Series A convertible preferred stock accretion	(951)				(951)
Net income	34,377				34,377
Other comprehensive income (loss)	(13,624)					(13,624)
Ending balance (shares) at Jun. 30, 2018		68,109	27,802
Ending balance at Jun. 30, 2018	198,226	$ 96	$ (360,032)	379,571	233,380	(54,789)
Beginning balance (shares) at Dec. 31, 2018		73,306	29,656
Beginning balance at Dec. 31, 2018	150,308	$ 103	$ (397,491)	481,133	121,215	(54,652)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	7,401			7,401
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units (shares)		954	49
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units	(1,030)	$ 1	$ (1,227)	196
Repurchases of common stock (shares)		(4,645)	(4,645)
Repurchases of common stock	(108,475)		$ (108,475)
Net income	63,908				63,908
Other comprehensive income (loss)	51					51
Ending balance (shares) at Jun. 30, 2019		69,615	34,350
Ending balance at Jun. 30, 2019	111,936	$ 104	$ (507,193)	488,730	184,896	(54,601)
Beginning balance (shares) at Mar. 31, 2019		72,009	31,838
Beginning balance at Mar. 31, 2019	122,945	$ 104	$ (452,196)	484,932	145,698	(55,593)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,767			3,767
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units (shares)		118	0
Exercises of stock options, issuance of restricted stock awards, and vests of restricted stock units	31	$ 0	$ 0	31
Repurchases of common stock (shares)		(2,512)	(2,512)
Repurchases of common stock	(54,997)		$ (54,997)
Net income	39,198				39,198
Other comprehensive income (loss)	992					992
Ending balance (shares) at Jun. 30, 2019		69,615	34,350
Ending balance at Jun. 30, 2019	$ 111,936	$ 104	$ (507,193)	$ 488,730	$ 184,896	$ (54,601)