Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 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)
Accumulated other comprehensive income (loss), beginning balance	(78,656)	(61,866)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	1,811	972
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		750
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	0
Accumulated other comprehensive income (loss), ending balance	(77,258)	(61,116)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	43,688	138,255
Other Comprehensive Income (Loss), Tax	(413)	(222)
Common stock, shares outstanding (in shares)			59,560,036
Stockholders' Equity Attributable to Parent		599,303	$ 855,497	460,342
Stock Issued During Period, Value, Restricted Stock Award, Gross	0	0
Issuance of common shares, net of withholdings		(1,115)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,750	1,821
NET EARNINGS	42,290	137,505
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances	(1,197)
reclassification of liability to equity	0
Amazon Warrant AB and C
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
reclassification of liability to equity	(9)
Accumulated Other Comprehensive Income (Loss) [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 1,398
Stockholders' Equity Attributable to Parent		$ (61,116)		$ (61,866)
Common Stock [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Common stock, shares outstanding (in shares)		59,623,195		59,329,431
Stockholders' Equity Attributable to Parent		$ 596		$ 593
Grant of restricted stock (in shares)	122,100	200,500
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 1	$ 2
Issuance of common shares, net of withholdings (in shares)		93,264
Issuance of common shares, net of withholdings		$ 1
Withholdings of common shares, net of issuances (in shares)	93,752
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances	$ 0
Additional Paid-in Capital [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Stockholders' Equity Attributable to Parent		476,423		475,720
Stock Issued During Period, Value, Restricted Stock Award, Gross	(1)	(2)
Issuance of common shares, net of withholdings		(1,116)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,750	1,821
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances	(1,197)
Accumulated Deficit [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	42,290	137,505
Stockholders' Equity Attributable to Parent		183,400		$ 45,895
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(78,093)	(61,152)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	1,764	941
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	(402)	(215)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	1,362	726
Accumulated other comprehensive income (loss), ending balance	(76,731)	(60,426)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(549)	(702)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	47	31
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, before Tax [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	(11)	(7)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	36	24
Accumulated other comprehensive income (loss), ending balance	$ (513)	$ (678)