Commitments and Contingencies - Contingencies (Details)			3 Months Ended
	Sep. 28, 2017 item	Jun. 15, 2016 plaintiff	Dec. 31, 2017 USD ($)
Securities Litigation Case | Pending Litigation
Commitments and Contingencies
Number of purported shareholders that have filed lawsuits | plaintiff		2
Loss contingency accrual			$ 0
Heckermann Montross Suit | Pending Litigation
Commitments and Contingencies
Loss contingency accrual			0
Gemalto Suit | Settled Litigation
Commitments and Contingencies
The number of patents involved in lawsuit | item	2
One-time settlement payment amount			$ 750,000
Period of no lawsuits upon settlement agreement	18 months