Revenue Recognition (Details) - USD ($)	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	$ 169,567,000	$ 139,039,000
Cost of revenue	40,198,000	32,532,000
Gross margin	129,369,000	106,507,000
Operating income	34,596,000	37,216,000
Income before income tax expense	37,979,000	39,235,000
Income tax expense (benefit)	762,000	(6,236,000)
Net income	$ 37,217,000	$ 45,471,000
Basic (in dollars per share)	$ 0.21	$ 0.26
Diluted (in dollars per share)	$ 0.21	$ 0.25
Prepaid expenses and other current assets	$ 26,068,000		$ 30,683,000
Accrued income taxes	11,915,000		11,503,000
Deferred revenue and customer deposits	15,504,000		9,420,000
Retained earnings	622,856,000		668,587,000
Revenues	169,567,000	$ 139,039,000
Costs to fulfill a contract	4,615,000		3,230,000
Change in Contract with Customer, Asset [Abstract]
Balance as of December 31, 2017	9,420,000
Increases to deferred revenue and customer deposits	11,751,000
Recognition of revenue	(5,875,000)
Foreign exchange rate changes	208,000
Balance as of April 1, 2018	15,504,000
Standard products and services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	158,399,000	133,017
Application-specific customer solutions
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	11,168,000	6,022
Americas
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	59,217,000	42,540,000
Europe
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	56,203,000	43,107,000
Greater China
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	27,159,000	22,706,000
Other Asia
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 26,988,000	30,686,000
As previously reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		134,942,000
Cost of revenue		28,225,000
Gross margin		106,717,000
Operating income		37,426,000
Income before income tax expense		39,445,000
Income tax expense (benefit)		(6,210,000)
Net income		$ 45,655,000
Basic (in dollars per share)		$ 0.26
Diluted (in dollars per share)		$ 0.26
Prepaid expenses and other current assets			30,800,000
Accrued income taxes			11,391,000
Deferred revenue and customer deposits			9,969,000
Retained earnings			668,267,000
Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue		$ 4,097,000
Cost of revenue		4,307,000
Gross margin		(210,000)
Operating income		(210,000)
Income before income tax expense		(210,000)
Income tax expense (benefit)		(26,000)
Net income		$ (184,000)
Basic (in dollars per share)		$ 0
Diluted (in dollars per share)		$ (10)
Prepaid expenses and other current assets			(117,000)
Accrued income taxes			112,000
Deferred revenue and customer deposits			(549,000)
Retained earnings			$ 320,000