Nature of Business and Significant Accounting Policies Nature of Business and Significant Accounting Policies (Details 8) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Balance Sheet
Accounts Receivable, Net	$ 323,746												$ 323,746			$ 347,668
Inventory, Net	352,107								$ 372,183				352,107	$ 372,183		371,659
Deferred income taxes, net	100,620								21,001				100,620	21,001		95,368
Other Assets																58,864
Deferred Revenue	32,703												32,703			24,826
Deferred income taxes	22,927								12,496				22,927	12,496		14,853
Pension and other long-term liabilities	3,417								3,887				3,417	3,887		51,842
Retained Earnings	2,024,523								1,856,756				2,024,523	1,856,756		1,937,036
Income Statement [Abstract]
Revenue	448,463		$ 434,898		$ 452,707		$ 439,618		494,784	$ 464,712	$ 434,124	$ 406,814	1,775,686	1,800,434	$ 1,662,167
Cost of Goods Sold													875,368	941,658	895,046
Income Tax provision													24,678	171,842	109,331
Net earnings	98,516	[1]	$ 73,151	[1]	$ 71,563	[1]	$ 39,195	[1]	(50,290)	$ 63,529	$ 51,413	$ 42,571	282,425	107,223	$ 166,626
Accounting Standards Update 2014-09 [Member]
Balance Sheet
Accounts Receivable, Net																0
Inventory, Net																0
Deferred income taxes, net																74,367
Other Assets																(1,005)
Deferred Revenue																0
Deferred income taxes																2,067
Pension and other long-term liabilities																(8,030)
Retained Earnings																79,325
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Balance Sheet
Accounts Receivable, Net	321,017								346,687				321,017	346,687
Inventory, Net	352,482								372,183				352,482	372,183
Deferred income taxes, net									21,001					21,001
Other Assets									59,869					59,869
Deferred Revenue	32,703								25,614				32,703	25,614
Deferred income taxes	22,348								12,496				22,348	12,496
Pension and other long-term liabilities									59,872					59,872
Retained Earnings	2,022,748								$ 1,856,756				2,022,748	$ 1,856,756
Income Statement [Abstract]
Revenue													1,773,938
Cost of Goods Sold													874,993
Income Tax provision													24,389
Net earnings													281,341
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Income Statement [Abstract]
Revenue													1,748
Cost of Goods Sold													375
Income Tax provision													289
Net earnings													1,084
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Balance Sheet
Accounts Receivable, Net	2,729												2,729			981
Inventory, Net	(375)												(375)			(524)
Deferred income taxes, net																0
Other Assets																0
Deferred Revenue	0												0			(788)
Deferred income taxes	579												579			290
Pension and other long-term liabilities																0
Retained Earnings	$ 1,775												$ 1,775			$ 955

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