Stock Compensation Plans (Summary of Total Share-Based Compensation Expense and Related Net Tax Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Total Share-based Stock Compensation Expense and Related Net Tax Benefit [Abstract]
Stock compensation costs	$ 8,208	$ 7,071	$ 16,025	$ 14,280
Related net tax benefits (deficiencies) for stock compensation plans	$ 37	$ (9)	$ 1,657	$ (1,575)

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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Balance Type:	credit
Period Type:	duration