CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 223,615	$ 811,020		$ 725,625		$ 806,338
Cost of revenue		206,421		189,754		206,052
Gross margin	168,455	604,599		535,871		600,286
Research, development, and engineering expenses		130,982		119,427		116,445
Selling, general, and administrative expenses		267,593		273,842		262,699
Restructuring charges	875	15,924		0		0
Intangible asset impairment charges	0	19,571		0		0
Operating income	59,085	170,529		142,602		221,142
Foreign currency gain (loss)		3,697		(509)		(1,064)
Investment income		12,994		19,689		14,715
Other income (expense)		(309)		1,212		(219)
Income before income tax expense (benefit)		186,911		162,994		234,574
Income tax expense on continuing operations		10,725		(40,871)		15,307
Net income	$ 69,345	$ 176,186		$ 203,865		$ 219,267
Net Income per weighted-average common and common-equivalent share:
Net income (in dollars per share)	$ 0.40	$ 1.02		$ 1.19		$ 1.27
Diluted earnings per weighted-average common and common-equivalent share (1):
Net income (in dollars per share)	0.39	$ 1.00		$ 1.16		$ 1.24
Weighted-average common and common-equivalent shares outstanding:
Basic (in shares)		173,489		171,194		172,333
Diluted (in shares)		176,592		175,269		177,406
Cash dividends per common share (in dollars per share)	$ 2.00	$ 2.225	[1]	$ 0.205	[1]	$ 0.185	[1]

[1] Prior period results have been adjusted to reflect the two-for-one stock split effected in the form of a stock dividend which occurred in the fourth quarter of 2017.
2