Stock-Based Compensation Plans Compensation Expense and Related Tax Benefits (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	$ 7,529	$ 7,413	$ 7,965
Tax benefits as a percentage of compensation expense	21.40%	21.70%	33.00%
Statutory tax rate	21.00%	21.00%	21.00%
Stock Options And Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 8,381	$ 7,413	$ 7,965
Tax benefit	(1,790)	(1,610)	(2,625)
Total stock-based compensation, net of tax	$ 6,591	$ 5,803	$ 5,340

Employee Service Share-based Compensation, Tax Benefit from Compensation Expense, Percent

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

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Amount, after tax, of expense for award under share-based payment arrangement.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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