CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Losses	Treasury Stock
Balance at beginning of period (in shares) at Dec. 31, 2018		55,135,788
Balance at beginning of period at Dec. 31, 2018	$ 473,849	$ 744	$ 629,039	$ 150,244	$ (3,343)	$ (302,835)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	14,780			14,780
Foreign currency translation	298				298
Stock-based compensation (in shares)		273,158
Stock-based compensation	2,586	$ 5	2,581
Stock repurchase	(2,635)					(2,635)
Common stock dividends	(4,512)			(4,512)
Unrealized loss on derivative instruments, net of tax	(814)				(814)
Stock option exercises (in shares)		15,187
Stock option exercises	54		54
Balance at end of period (in shares) at Mar. 31, 2019		55,424,133
Balance at end of period at Mar. 31, 2019	483,606	$ 749	631,674	160,512	(3,859)	(305,470)
Balance at beginning of period (in shares) at Dec. 31, 2018		55,135,788
Balance at beginning of period at Dec. 31, 2018	473,849	$ 744	629,039	150,244	(3,343)	(302,835)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	71,200
Foreign currency translation	(280)
Balance at end of period (in shares) at Sep. 30, 2019		54,122,624
Balance at end of period at Sep. 30, 2019	515,058	$ 750	636,756	207,934	(4,895)	(325,487)
Balance at beginning of period (in shares) at Mar. 31, 2019		55,424,133
Balance at beginning of period at Mar. 31, 2019	483,606	$ 749	631,674	160,512	(3,859)	(305,470)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	30,960			30,960
Foreign currency translation	(115)				(115)
Stock-based compensation (in shares)		26,639
Stock-based compensation	2,791		2,791
Stock repurchase (in shares)		(775,081)
Stock repurchase	(11,217)					(11,217)
Common stock dividends	(4,538)			(4,538)
Unrealized loss on derivative instruments, net of tax	78				78
Balance at end of period (in shares) at Jun. 30, 2019		54,675,691
Balance at end of period at Jun. 30, 2019	501,565	$ 749	634,465	186,934	(3,896)	(316,687)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	25,460			25,460
Foreign currency translation	(463)				(463)
Stock-based compensation (in shares)		8,176
Stock-based compensation	1,963		1,985			(22)
Stock repurchase (in shares)		(590,256)
Stock repurchase	(8,778)					(8,778)
Common stock dividends	(4,460)			(4,460)
Unrealized loss on derivative instruments, net of tax	(536)				(536)
Stock option exercises (in shares)		29,013
Stock option exercises	307	$ 1	306
Balance at end of period (in shares) at Sep. 30, 2019		54,122,624
Balance at end of period at Sep. 30, 2019	515,058	$ 750	636,756	207,934	(4,895)	(325,487)
Balance at beginning of period (in shares) at Dec. 31, 2019		53,473,620
Balance at beginning of period at Dec. 31, 2019	520,988	$ 750	638,917	221,841	(3,978)	(336,542)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	(106,647)			(106,647)
Foreign currency translation	(1,636)				(1,636)
Stock-based compensation (in shares)		141,223
Stock-based compensation	(917)	$ 3	(920)
Stock repurchase (in shares)		(766,122)
Stock repurchase	(10,051)					(10,051)
Common stock dividends	(3,885)			(3,885)
Unrealized loss on derivative instruments, net of tax	(3,883)				(3,883)
Balance at end of period (in shares) at Mar. 31, 2020		52,848,721
Balance at end of period at Mar. 31, 2020	393,969	$ 753	637,997	111,309	(9,497)	(346,593)
Balance at beginning of period (in shares) at Dec. 31, 2019		53,473,620
Balance at beginning of period at Dec. 31, 2019	520,988	$ 750	638,917	221,841	(3,978)	(336,542)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	(102,906)
Foreign currency translation	(1,056)
Balance at end of period (in shares) at Sep. 30, 2020		52,912,988
Balance at end of period at Sep. 30, 2020	397,365	$ 753	641,236	106,118	(4,135)	(346,607)
Balance at beginning of period (in shares) at Mar. 31, 2020		52,848,721
Balance at beginning of period at Mar. 31, 2020	393,969	$ 753	637,997	111,309	(9,497)	(346,593)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	(146)			(146)
Foreign currency translation	318				318
Stock-based compensation (in shares)		57,394
Stock-based compensation	1,333		1,333
Stock repurchase	(14)					(14)
Common stock dividends	(4,507)			(4,507)
Unrealized loss on derivative instruments, net of tax	2,264				2,264
Balance at end of period (in shares) at Jun. 30, 2020		52,906,115
Balance at end of period at Jun. 30, 2020	393,217	$ 753	639,330	106,656	(6,915)	(346,607)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss for the period	3,887			3,887
Foreign currency translation	262				262
Stock-based compensation (in shares)		2,253
Stock-based compensation	1,862		1,862
Common stock dividends	(4,425)			(4,425)
Unrealized loss on derivative instruments, net of tax	2,518				2,518
Stock option exercises (in shares)		4,620
Stock option exercises	44		44
Balance at end of period (in shares) at Sep. 30, 2020		52,912,988
Balance at end of period at Sep. 30, 2020	$ 397,365	$ 753	$ 641,236	$ 106,118	$ (4,135)	$ (346,607)