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Stock-Based Compensation and Directors Stock Purchase Plan Stock-Based Compensation and Directors Stock Purchase Plan (Additional Information About Stock Options and SARs Exercises) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Noncash Expense [Abstract]
Intrinsic value of options and SARs exercised	$ 6,278	$ 7,109	$ 9,632
Tax benefit realized from options and SARs exercised	$ 1,252	$ 1,385	$ 1,928

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Options Exercises And Stock Appreciation Rights Exercises In Period Total Intrinsic Value

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No definition available.

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- Definition

Tax benefit realized from options and stock appreciation rights exercised.

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No definition available.

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