Business Segment Information (Reconciliation of Total Operating Profit) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total operating profit from segments	$ 136,874	$ 127,362	$ 397,179	$ 385,424
Income from operations	120,637	112,420	344,334	339,026
Operating Segments
Segment Reporting Information [Line Items]
Total operating profit from segments	136,874	127,362	397,179	385,424
Corporate
Segment Reporting Information [Line Items]
Corporate overhead expenses	$ (16,237)	$ (14,942)	$ (52,845)	$ (46,398)

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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