Accounting for Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 24,570	$ 26,031	$ 19,581
Stock-Based Compensation Unrecognized	22,077
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	11,895	10,644	7,410
Stock-Based Compensation Unrecognized	$ 10,777
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 8 months 12 days
Cash Settled RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 7,015	10,213	8,214
Stock-Based Compensation Unrecognized	$ 8,688
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 6 months
Non-Employee Director Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 755	719	764
Stock-Based Compensation Unrecognized	$ 383
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	4 months 24 days
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 4,905	$ 4,455	$ 3,193
Stock-Based Compensation Unrecognized	$ 2,229
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 6 months

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

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