Stock Compensation Plans (Summary of Total Share-Based Compensation Expense and Related Net Tax Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Total Stock Compensation Expense and Related Net Tax Benefit [Abstract]
Stock compensation costs	$ 7,487	$ 10,986	$ 23,012	$ 24,201
Related net tax benefits for stock compensation plans	$ 15	$ 187	$ 4,723	$ 5,062

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=116856206&loc=d3e5070-113901

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