CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Retailed Earnings	Additional Paid-in Capital	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2018		44,877,000
Beginning balance at Dec. 31, 2018	$ 754,052	$ 449	$ 226,765	$ 530,919	$ (4,081)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Stock based compensation (in shares)		128,000
Stock based compensation	2,233	$ 1		2,232
Net income	17,444		17,444
Cash dividends paid	(11,219)		(11,219)
Other comprehensive income (loss)	706				706
Ending balance (in shares) at Jun. 30, 2019		45,005,000
Ending balance at Jun. 30, 2019	763,216	$ 450	232,990	533,151	(3,375)
Beginning balance (in shares) at Mar. 31, 2019		44,877,000
Beginning balance at Mar. 31, 2019	778,420	$ 449	249,488	532,208	(3,725)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Stock based compensation (in shares)		128,000
Stock based compensation	944	$ 1		943
Net income	(10,889)		(10,889)
Cash dividends paid	(5,609)		(5,609)
Other comprehensive income (loss)	350				350
Ending balance (in shares) at Jun. 30, 2019		45,005,000
Ending balance at Jun. 30, 2019	$ 763,216	$ 450	232,990	533,151	(3,375)
Beginning balance (in shares) at Dec. 31, 2019	45,108,545	45,109,000
Beginning balance at Dec. 31, 2019	$ 668,741	$ 451	136,502	535,094	(3,306)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Stock based compensation (in shares)		653,000
Stock based compensation	1,246	$ 7		1,239
Net income	(99,176)		(99,176)
Other comprehensive income (loss)	$ (746)				(746)
Ending balance (in shares) at Jun. 30, 2020	45,762,200	45,762,000
Ending balance at Jun. 30, 2020	$ 570,065	$ 458	37,326	536,333	(4,052)
Beginning balance (in shares) at Mar. 31, 2020		45,714,000
Beginning balance at Mar. 31, 2020	584,408	$ 457	52,531	536,140	(4,720)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Stock based compensation (in shares)		48,000
Stock based compensation	194	$ 1		193
Net income	(15,205)		(15,205)
Other comprehensive income (loss)	$ 668				668
Ending balance (in shares) at Jun. 30, 2020	45,762,200	45,762,000
Ending balance at Jun. 30, 2020	$ 570,065	$ 458	$ 37,326	$ 536,333	$ (4,052)