Basis of Presentation and Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Balance Sheet
Accounts receivable, net	$ 304,265		$ 304,265		$ 347,668	$ 346,687
Inventories	384,242		384,242		371,659	372,183
Other assets	85,382		85,382		58,864	59,869
Deferred revenue	27,299		27,299		24,826	25,614
Deferred income taxes	15,294		15,294		14,208	12,496
Pension and other long term liabilities	67,024		67,024		51,842	59,872
Retained earnings	1,929,742		1,929,742		1,863,314	1,856,756
Income Statement
Revenue	452,707	$ 434,124	892,325	$ 840,938
Cost of goods sold	220,156	227,392	441,860	442,885
Income tax provision	11,390	12,127	26,810	25,120
Net earnings	71,563	$ 51,413	110,758	$ 93,984
Calculated under Revenue Guidance in Effect before Topic 606
Balance Sheet
Accounts receivable, net	302,128		302,128			346,687
Inventories	384,449		384,449			372,183
Other assets						59,869
Deferred revenue	27,299		27,299			25,614
Deferred income taxes	14,804		14,804			12,496
Pension and other long term liabilities						59,872
Retained earnings	1,928,302		1,928,302			$ 1,856,756
Income Statement
Revenue	452,198		891,169
Cost of goods sold	220,043		441,653
Income tax provision	11,309		26,610
Net earnings	71,248		110,009
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Balance Sheet
Accounts receivable, net	2,137		2,137		981
Inventories	(207)		(207)		(524)
Other assets					0
Deferred revenue	0		0		(788)
Deferred income taxes	490		490		290
Pension and other long term liabilities					0
Retained earnings	1,440		1,440		955
Income Statement
Revenue	509		1,156
Cost of goods sold	113		207
Income tax provision	81		200
Net earnings	$ 315		$ 749
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