CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock Common Class A	Common Stock Common Class B	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2019	$ 881,443	$ 1,339	$ 40	$ 1,655,781	$ (775,578)	$ (139)
Beginning balance (in shares) at Dec. 31, 2019		133,867,621	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(9,138)				(9,138)
Compensation expense related to granting of stock awards (in shares)		440,129
Compensation expense related to granting of stock awards	4,117	$ 4		4,113
Issuance of common stock related to the Employee Stock Purchase Plan (ESPP) (in shares)		165,756
Issuance of common stock related to the Employee Stock Purchase Plan ("ESPP")	241	$ 2		239
Purchase of vested employee restricted stock units (in shares)		(432,472)
Purchase of vested employee restricted stock units	(1,394)	$ (4)		(1,390)
Payment of dividends on common stock	(3,221)			(3,221)
Dividend equivalents, net of forfeitures	493			493
Net unrealized gain (loss) on derivatives	(2,354)					(2,354)
Ending balance at Mar. 31, 2020	870,187	$ 1,341	$ 40	1,656,015	(784,716)	(2,493)
Ending balance (in shares) at Mar. 31, 2020		134,041,034	4,045,199
Beginning balance at Dec. 31, 2019	881,443	$ 1,339	$ 40	1,655,781	(775,578)	(139)
Beginning balance (in shares) at Dec. 31, 2019		133,867,621	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(79,827)
Net unrealized gain (loss) on derivatives	(2,099)
Ending balance at Sep. 30, 2020	803,687	$ 1,340	$ 40	1,659,950	(855,405)	(2,238)
Ending balance (in shares) at Sep. 30, 2020		133,949,367	4,045,199
Beginning balance at Mar. 31, 2020	870,187	$ 1,341	$ 40	1,656,015	(784,716)	(2,493)
Beginning balance (in shares) at Mar. 31, 2020		134,041,034	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(53,811)				(53,811)
Compensation expense related to granting of stock awards (in shares)		(30,040)
Compensation expense related to granting of stock awards	2,274			2,274
Purchase of vested employee restricted stock units (in shares)		(41,002)
Purchase of vested employee restricted stock units	(53)	$ (1)		(52)
Payment of dividends on common stock	(189)			(189)
Dividend equivalents, net of forfeitures	162			162
Net unrealized gain (loss) on derivatives	(260)					(260)
Ending balance at Jun. 30, 2020	818,310	$ 1,340	$ 40	1,658,210	(838,527)	(2,753)
Ending balance (in shares) at Jun. 30, 2020		133,969,992	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(16,878)				(16,878)
Compensation expense related to granting of stock awards (in shares)		(20,625)
Compensation expense related to granting of stock awards	1,784			1,784
Dividend equivalents, net of forfeitures	(44)			(44)
Net unrealized gain (loss) on derivatives	515					515
Ending balance at Sep. 30, 2020	803,687	$ 1,340	$ 40	1,659,950	(855,405)	(2,238)
Ending balance (in shares) at Sep. 30, 2020		133,949,367	4,045,199
Beginning balance at Dec. 31, 2020	644,738	$ 1,369	$ 40	1,662,155	(1,017,037)	(1,789)
Beginning balance (in shares) at Dec. 31, 2020		136,913,375	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(21,648)				(21,648)
Compensation expense related to granting of stock awards (in shares)		291,347
Compensation expense related to granting of stock awards	2,578	$ 3		2,575
Exercise of stock options (in shares)		47,535
Exercise of stock options	15			15
Purchase of vested employee restricted stock units (in shares)		(347,607)
Purchase of vested employee restricted stock units	(1,911)	$ (3)		(1,908)
Payment of dividends on common stock	(386)			(386)
Dividend equivalents, net of forfeitures	386				386
Net unrealized gain (loss) on derivatives	553					553
Ending balance at Mar. 31, 2021	624,325	$ 1,369	$ 40	1,662,451	(1,038,299)	(1,236)
Ending balance (in shares) at Mar. 31, 2021		136,904,650	4,045,199
Beginning balance at Dec. 31, 2020	644,738	$ 1,369	$ 40	1,662,155	(1,017,037)	(1,789)
Beginning balance (in shares) at Dec. 31, 2020		136,913,375	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (24,982)
Exercise of stock options (in shares)	115,000
Net unrealized gain (loss) on derivatives	$ 929
Ending balance at Sep. 30, 2021	627,194	$ 1,373	$ 40	1,668,065	(1,041,424)	(860)
Ending balance (in shares) at Sep. 30, 2021		137,298,864	4,045,199
Beginning balance at Mar. 31, 2021	624,325	$ 1,369	$ 40	1,662,451	(1,038,299)	(1,236)
Beginning balance (in shares) at Mar. 31, 2021		136,904,650	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,426				1,426
Compensation expense related to granting of stock awards (in shares)		412,243
Compensation expense related to granting of stock awards	2,445	$ 4		2,441
Exercise of stock options (in shares)		38,399
Exercise of stock options	17			17
Purchase of vested employee restricted stock units (in shares)		(20,317)
Purchase of vested employee restricted stock units	(98)			(98)
Payment of dividends on common stock	(194)			(194)
Dividend equivalents, net of forfeitures	201				201	0
Net unrealized gain (loss) on derivatives	206					206
Ending balance at Jun. 30, 2021	628,328	$ 1,373	$ 40	1,664,617	(1,036,672)	(1,030)
Ending balance (in shares) at Jun. 30, 2021		137,334,975	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(4,761)				(4,761)
Compensation expense related to granting of stock awards (in shares)		(94,466)
Compensation expense related to granting of stock awards	3,325	$ (1)		3,326
Issuance of common stock related to the Employee Stock Purchase Plan (ESPP) (in shares)		38,782
Issuance of common stock related to the Employee Stock Purchase Plan ("ESPP")	142			142
Exercise of stock options (in shares)		28,800
Exercise of stock options	13	$ 1		12
Purchase of vested employee restricted stock units (in shares)		(9,227)
Purchase of vested employee restricted stock units	(31)			(31)
Payment of dividends on common stock	(1)			(1)
Dividend equivalents, net of forfeitures	9				9
Net unrealized gain (loss) on derivatives	170					170
Ending balance at Sep. 30, 2021	$ 627,194	$ 1,373	$ 40	$ 1,668,065	$ (1,041,424)	$ (860)
Ending balance (in shares) at Sep. 30, 2021		137,298,864	4,045,199