Stock Compensation Plans (Summary of Total Share-Based Compensation Expense and Related Tax Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Stock compensation costs	$ 29,237	$ 30,761	$ 30,937
Excess tax benefits related to stock compensation expense recognized in income tax expense	$ (1,839)	$ 4,792	$ 5,089

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

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 (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration