Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (14)	$ (12)	$ (14)	$ (12)	$ (14)	$ (14)	$ (12)	$ (12)
Accumulated other comprehensive income (loss), beginning balance	(77,258)	(61,116)	(78,656)	(61,866)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	1,811	972	3,622	1,944
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0	0	0	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	1,398	750		1,500
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	0	0	0
Accumulated other comprehensive income (loss), ending balance	(75,860)	(60,366)	(75,860)	(60,366)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	81,332	(104,176)	125,020	34,079
Other Comprehensive Income (Loss), Tax	$ (413)	(222)	$ (826)	(444)
Common stock, shares outstanding (in shares)	74,202,815		74,202,815			59,560,036
Stockholders' Equity Attributable to Parent	$ 1,114,727	496,533	$ 1,114,727	496,533	899,738	$ 855,497	599,303	460,342
Stock Issued During Period, Value, Restricted Stock Award, Gross	0	0	0	0
Withholdings of common shares, net of issuances	(39)	(724)	(1,236)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,729	2,130	3,479	3,951
NET EARNINGS (LOSS)	79,934	(104,926)	122,224	32,579
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances				(1,839)
Accumulated Other Comprehensive Income (Loss) [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent			2,796
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			122,224
Stockholders' Equity Attributable to Parent	$ (75,860)	$ (60,366)	$ (75,860)	$ (60,366)	$ (77,258)	$ (78,656)	$ (61,116)	$ (61,866)
Common Stock [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Common stock, shares outstanding (in shares)	74,202,815	59,589,770	74,202,815	59,589,770	60,641,436	59,560,036	59,623,195	59,329,431
Stockholders' Equity Attributable to Parent	$ 742	$ 596	$ 742	$ 596	$ 606	$ 596	$ 596	$ 593
Grant of restricted stock (in shares)	0	900	122,100	201,400
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 0	$ 0	$ 1	$ 2
Issuance of common shares, net of withholdings (in shares)	(1,518)	(33,825)	92,234
Withholdings of common shares, net of issuances	$ 0	$ 0	$ 1
Withholdings of common shares, net of issuances (in shares)				59,439
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances				$ 1
Additional Paid-in Capital [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Stockholders' Equity Attributable to Parent	989,611	477,829	989,611	477,829	856,090	855,547	476,423	475,720
Stock Issued During Period, Value, Restricted Stock Award, Gross	0	0	(1)	(2)
Withholdings of common shares, net of issuances	(39)	(724)	(1,237)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,729	2,130	3,479	3,951
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances				(1,840)
Accumulated Deficit [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	79,934	(104,926)		32,579
Stockholders' Equity Attributable to Parent	200,234	78,474	200,234	78,474	$ 120,300	$ 78,010	$ 183,400	$ 45,895
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(76,731)	(60,426)	(78,093)	(61,152)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	1,764	941	3,528	1,882
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	(402)	(215)	(804)	(430)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	1,362	726	2,724	1,452
Accumulated other comprehensive income (loss), ending balance	(75,369)	(59,700)	(75,369)	(59,700)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(513)	(678)	(549)	(702)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	47	31	94	62
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	(11)	(7)	(22)	(14)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	36	24	72	48
Accumulated other comprehensive income (loss), ending balance	$ (477)	$ (654)	$ (477)	$ (654)