Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (75,985)	$ (53,315)	$ (52,830)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,738	4,915	4,061
Stock-based compensation expense	13,858	16,830	20,940
Acquisition-related share-based awards acceleration expense	0	0	2,648
Amortization of developed technology	11,200	11,200	9,800
Non-cash charges for sale of inventory revalued at the date of acquisition	0	0	856
Other non-cash items	252	137	0
Loss on disposal of property and equipment	87	87	83
Gain from escrow settlement	0	(3,986)	0
Gain from sale of investment in Verinata	0	(2,330)	(332)
Changes in assets and liabilities:
Accounts receivable	10,521	(2,762)	(3,393)
Inventories	(3,387)	(3,741)	(6,162)
Prepaid expenses and other assets	(457)	(1,127)	(52)
Accounts payable	(2,271)	769	107
Deferred revenue	(274)	2,613	3,191
Other liabilities	620	(3,986)	(1,540)
Net cash used in operating activities	(39,098)	(34,696)	(22,623)
Investing activities
Acquisition, net of cash acquired	0	0	(113,190)
Purchases of investments	(38,594)	(66,973)	(132,644)
Proceeds from sales and maturities of investments	86,431	103,369	74,520
Proceeds from sale of investment in Verinata	2,330	0	332
Purchase of intangible assets	0	(6,670)	0
Purchases of property and equipment	(5,065)	(3,982)	(7,403)
Net cash provided by (used in) investing activities	45,102	25,744	(178,385)
Financing activities
Proceeds from issuance of convertible notes, net	0	0	195,213
Proceeds from issuance of common stock through stock plan, net of tax payment	76	5,303	5,113
Net cash provided by financing activities	76	5,303	200,326
Effect of foreign exchange rate fluctuations on cash and cash equivalents	(152)	(947)	(866)
Net increase (decrease) in cash and cash equivalents	5,928	(4,596)	(1,548)
Cash and cash equivalents at beginning of period	29,117	33,713	35,261
Cash and cash equivalents at end of period	35,045	29,117	33,713
Supplemental disclosures of cash flow information
Cash paid for interest	5,534	5,538	2,750
Cash paid for income taxes	355	189	187
Non-cash investing and financing activities
Issuance of common stock and options related to acquisition	$ 0	$ 0	$ 78,196