Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Amazon Warrant AB and C	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at at Dec. 31, 2019	$ 460,342		$ 593	$ 475,720	$ 45,895	$ (61,866)
Balance at (in shares) at Dec. 31, 2019			59,329,431
Stock-based compensation plans
Stock Issued During Period, Value, Restricted Stock Award, Gross	0		$ 2	(2)
Grant of restricted stock (in shares)			201,400
Stock Issued During Period, Value, Share-based Compensation, Withholdings of Common Shares, Net of Issuances	(1,839)		$ 1	(1,840)
Withholdings of common shares, net of issuances (in shares)			59,439
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	0		$ 0	0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	5,786			5,786
Forfeited restricted stock (in shares)			(500)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	29,238				26,988
Balance at at Sep. 30, 2020	714,620		$ 596	700,757	72,883	(59,616)
Balance at (in shares) at Sep. 30, 2020			59,589,770
Stock-based compensation plans
reclassification of liability to equity	221,093	$ 221,093
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	2,250
Balance at at Jun. 30, 2020	496,533		$ 596	477,829	78,474	(60,366)
Balance at (in shares) at Jun. 30, 2020			59,589,770
Stock-based compensation plans
Stock Issued During Period, Value, Restricted Stock Award, Gross	0		$ 0	0
Grant of restricted stock (in shares)			0
Withholdings of common shares, net of issuances	0		$ 0	0
Issuance of common shares, net of withholdings (in shares)			0
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	0		$ 0	0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	1,835			1,835
Forfeited restricted stock (in shares)			0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(4,841)				(5,591)
Balance at at Sep. 30, 2020	714,620		$ 596	700,757	72,883	(59,616)
Balance at (in shares) at Sep. 30, 2020			59,589,770
Stock-based compensation plans
reclassification of liability to equity	221,093	$ 221,093
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	750
Balance at at Dec. 31, 2020	$ 855,497		$ 596	855,547	78,010	(78,656)
Balance at (in shares) at Dec. 31, 2020	59,560,036		59,560,036
Stock-based compensation plans
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 0		$ 1	(1)
Grant of restricted stock (in shares)			121,339
Withholdings of common shares, net of issuances	(1,241)		$ 1	(1,242)
Issuance of common shares, net of withholdings (in shares)			92,234
Conversion of Stock, Amount Converted	131,967		$ 144	131,823
Conversion of Stock, Shares Converted			14,428,445
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	0		$ 0	0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	5,523			5,523
Forfeited restricted stock (in shares)			(2,800)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	191,090					186,896
Balance at at Sep. 30, 2021	$ 1,182,836		$ 742	991,650	264,906	(74,462)
Balance at (in shares) at Sep. 30, 2021	74,199,254		74,199,254
Stock-based compensation plans
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent						4,194
Balance at at Jun. 30, 2021	$ 1,114,727		$ 742	989,611	200,234	(75,860)
Balance at (in shares) at Jun. 30, 2021			74,202,815
Stock-based compensation plans
Stock Issued During Period, Value, Restricted Stock Award, Gross	0		$ 0	0
Grant of restricted stock (in shares)			(761)
Withholdings of common shares, net of issuances	(5)		$ 0	(5)
Issuance of common shares, net of withholdings (in shares)			0
Conversion of Stock, Amount Converted	0		$ 0	0
Conversion of Stock, Shares Converted
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	0		$ 0	0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	2,044			2,044
Forfeited restricted stock (in shares)			(2,800)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	66,070				64,672
Balance at at Sep. 30, 2021	$ 1,182,836		$ 742	$ 991,650	$ 264,906	$ (74,462)
Balance at (in shares) at Sep. 30, 2021	74,199,254		74,199,254
Stock-based compensation plans
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 1,398