Stock-Based Compensation - Summary of restricted stock unit activity (Details) - Restricted stock units - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Performance and Incentive Pay
Non-vested at beginning of year	$ 2,912	$ 2,509
Granted	5,709	0
Canceled/forfeited	(629)	(1,369)
Stock-based compensation expense	(1,586)	(642)
Non-vested at end of period	$ 6,406	$ 498

Share-based Payment Arrangement, Cost Recognized, Forfeitures in Period

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- Definition

Share-based Payment Arrangement, Cost Recognized, Granted in Period

+ References

No definition available.

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- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
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-Section S99
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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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