CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Operating activities
Net income (loss)	$ 4,159	$ (10,276)
Adjustments to reconcile net income (loss) to net cash and cash equivalents used in operating activities:
Depreciation and amortization	2,877	3,744
Net amortization of investment premiums and discounts	53	96
Equity-based compensation	3,012	2,896
Change in the fair value of acquisition-related contingent consideration	(181)	(90)
Deferred income taxes	(1)	9
Gain on disposal of equipment		(8)
Changes in operating assets and liabilities	(11,658)	577
Total adjustments	(5,898)	7,224
Net cash and cash equivalents used in operating activities	(1,739)	(3,052)
Investing activities
Purchases of investments	(21,968)	(10,433)
Proceeds from sales and maturities of investments	18,916	22,180
Proceeds from sale of equipment		8
Purchases of leasehold improvements and equipment	(3,553)	(2,535)
Decrease (increase) in restricted cash	202	(178)
Net cash and cash equivalents (used in) provided by investing activities	(6,403)	9,042
Financing activities
Net proceeds from issuance of common stock	2,344	1,482
Taxes paid related to net share settlement	(1,988)	(403)
Payment of acquisition-related contingent consideration	(174)
Net cash and cash equivalents provided by financing activities	182	1,079
Effect of exchange rate changes on cash	114	8
Net increase (decrease) in cash and cash equivalents	(7,846)	7,077
Cash and cash equivalents at beginning of period	27,043	13,746
Cash and cash equivalents at end of period	$ 19,197	$ 20,823