Income Taxes - Tax rate reconciliation (Details)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Reconciliation of federal statutory tax rate to effective tax rate
Federal statutory rate (as a percent)	21.00%	35.00%	35.00%
Foreign tax rate benefit (as a percent)	(12.90%)	(25.40%)	(22.60%)
Research and development tax credits (as a percent)	(9.80%)	(4.50%)	(4.10%)
GILTI and Subpart F income	4.30%	1.40%	1.40%
Nondeductible (nontaxable) foreign expenses	3.90%	1.10%	(4.00%)
State tax expense	1.50%	0.90%	0.60%
Release of prior year unrecognized tax benefits (as a percent)	(2.70%)	(0.60%)	(1.70%)
Excess officer compensation (as a percent)	2.40%	1.50%	1.40%
Other tax effects of equity compensation	(0.40%)	(2.20%)	(1.50%)
Change in cost-sharing treatment of stock-based compensation	(2.20%)	5.20%	(0.50%)
Excess tax benefit of stock-based compensation	(5.90%)	(5.60%)
Change in prior period valuation allowance	(2.50%)	(1.30%)	(0.60%)
Transition Tax On unremitted foreign earnings	(8.40%)	70.80%
Revaluation of deferred tax balances	0.30%	28.20%
Other deferred tax impacts of tax reform	(3.10%)	(64.80%)
Other (as a percent)	(1.30%)	(0.90%)	1.30%
Effective Tax Rate (as a percent)	(15.80%)	38.80%	4.70%