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, 2018	$ 1,334,260	$ 1,372	$ 40	$ 1,693,512	$ (360,664)	$ 0
Beginning Balance (in shares) at Dec. 31, 2018		137,180,213	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	3,125				3,125
Compensation expense related to granting of stock awards	3,573	$ 14		3,559
Compensation expense related to granting of stock awards (in shares)		1,406,722
Issuance of common stock related to the Employee Stock Purchase Plan ("ESPP")	379	$ 1		378
Issuance of common stock related to the Employee Stock Purchase Plan (ESPP) (in shares)		84,958
Exercise of stock options	244	$ 2		242
Exercise of stock options (in shares)		180,300
Purchase of vested employee restricted stock units	(1,426)	$ (2)		(1,424)
Purchase of vested employee restricted stock units (in shares)		(204,499)
Payment of dividends on common stock	(12,913)			(12,913)
Dividend equivalents, net of forfeitures	(463)			(463)
Ending Balance at Mar. 31, 2019	1,331,498	$ 1,387	$ 40	1,682,891	(352,820)	0
Ending Balance (in shares) at Mar. 31, 2019		138,647,694	4,045,199
Beginning Balance at Dec. 31, 2018	1,334,260	$ 1,372	$ 40	1,693,512	(360,664)	0
Beginning Balance (in shares) at Dec. 31, 2018		137,180,213	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	29,116
Net unrealized gain (loss) on derivatives	(224)
Ending Balance at Jun. 30, 2019	1,347,642	$ 1,386	$ 40	1,673,268	(326,828)	(224)
Ending Balance (in shares) at Jun. 30, 2019		138,465,883	4,045,199
Beginning Balance at Mar. 31, 2019	1,331,498	$ 1,387	$ 40	1,682,891	(352,820)	0
Beginning Balance (in shares) at Mar. 31, 2019		138,647,694	4,045,199
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	25,992				25,992
Compensation expense related to granting of stock awards	3,393			3,393
Compensation expense related to granting of stock awards (in shares)		(38,774)
Issuance of common stock related to the Employee Stock Purchase Plan ("ESPP")	364	$ 1		363
Issuance of common stock related to the Employee Stock Purchase Plan (ESPP) (in shares)		73,791
Purchase of vested employee restricted stock units	(1,300)	$ (2)		(1,298)
Purchase of vested employee restricted stock units (in shares)		(216,828)
Payment of dividends on common stock	(13,140)			(13,140)
Dividend equivalents, net of forfeitures	1,059			1,059
Net unrealized gain (loss) on derivatives	(224)					(224)
Ending Balance at Jun. 30, 2019	1,347,642	$ 1,386	$ 40	1,673,268	(326,828)	(224)
Ending Balance (in shares) at Jun. 30, 2019		138,465,883	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)	(9,138)				(9,138)
Compensation expense related to granting of stock awards	4,117	$ 4		4,113
Compensation expense related to granting of stock awards (in shares)		440,129
Issuance of common stock related to the Employee Stock Purchase Plan ("ESPP")	241	$ 2		239
Issuance of common stock related to the Employee Stock Purchase Plan (ESPP) (in shares)		165,756
Purchase of vested employee restricted stock units	(1,394)	$ (4)		(1,390)
Purchase of vested employee restricted stock units (in shares)		(432,472)
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)	$ (62,949)
Compensation expense related to granting of stock awards (in shares)	66,000
Net unrealized gain (loss) on derivatives	$ (2,614)
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
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	2,274			2,274
Compensation expense related to granting of stock awards (in shares)		(30,040)
Purchase of vested employee restricted stock units	(53)	$ (1)		(52)
Purchase of vested employee restricted stock units (in shares)		(41,002)
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