Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017
Effective Income Tax Rate	21.60%	54.80%	20.60%	45.20%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%	21.00%	35.00%
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 5,251		$ 12,142
(Provision for) benefit from income taxes	(107,668)	$ (17,298)	(114,250)	$ (28,639)
Unrecognized Tax Benefits, Increase Resulting from Divestiture	3,554		2,547
Decrease in Unrecognized Tax Benefits is Reasonably Possible	11,241		11,241
Income Taxes Receivable	5,851		5,851		$ 26,262
Income Taxes Receivable, Noncurrent	$ 0		0		$ 0
Tax Act
(Provision for) benefit from income taxes			(2,076)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount			2,426
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount			991
Release of valuation allowances on foreign tax credits			$ 1,341
System Optimization
(Provision for) benefit from income taxes		$ (5,019)