Basis of Presentation and Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Balance Sheet
Accounts receivable, net	$ 329,792		$ 347,668	$ 346,687
Inventories	385,906		371,659	372,183
Other assets	76,948		58,864	59,869
Deferred revenue	25,224		24,826	25,614
Deferred income taxes	15,732		14,208	12,496
Pension and other long term liabilities	67,249		51,842	59,872
Retained earnings	1,880,277		1,863,314	1,856,756
Income Statement
Revenue	439,618	$ 406,814
Cost of goods sold	221,704	215,493
Income tax provision	15,420	12,993
Net earnings	39,195	$ 42,571
Calculated under Revenue Guidance in Effect before Topic 606
Balance Sheet
Accounts receivable, net	328,164			346,687
Inventories	386,524			372,183
Other assets				59,869
Deferred revenue	26,012			25,614
Deferred income taxes	15,323			12,496
Pension and other long term liabilities				59,872
Retained earnings	1,878,888			$ 1,856,756
Income Statement
Revenue	438,971
Cost of goods sold	221,610
Income tax provision	15,301
Net earnings	38,761
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Balance Sheet
Accounts receivable, net	1,628		981
Inventories	(618)		(524)
Other assets			0
Deferred revenue	(788)		(788)
Deferred income taxes	409		290
Pension and other long term liabilities			0
Retained earnings	1,389		955
Income Statement
Revenue	647
Cost of goods sold	94
Income tax provision	119
Net earnings	$ 434
Restatement Adjustment | Accounting Standards Update 2016-16
Balance Sheet
Accounts receivable, net			0
Inventories			0
Other assets			(1,005)
Deferred revenue			0
Deferred income taxes			1,422
Pension and other long term liabilities			(8,030)
Retained earnings			$ 5,603