Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net loss	$ (123,355)	$ (77,583)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	13,507	11,528
Stock-based compensation expense	18,060	13,526
Amortization of premiums and discounts on marketable securities	17	215
Loss on extinguishment of debt	284
Gain on disposal of long-lived assets	(327)
Changes in operating assets and liabilities:
Accounts receivable	(5,087)	461
Receivable from Roche	(196)	(6,414)
Inventory	186	(3,967)
Prepaid expenses and other current assets	670	3,544
Other assets	173	(167)
Accounts payable	5,732	5,550
Accrued expenses and other current liabilities	5,222	7,205
Deferred rent and other non-current liabilities	(163)	(1,329)
Deferred revenue	(403)	1,439
Roche related-party deferred revenue	(3,451)	(3,447)
Net cash used in operating activities	(89,131)	(49,439)
Investing activities
Purchases of property and equipment	(9,971)	(14,007)
Purchases of marketable securities and other investments	(4,996)	(77,445)
Proceeds from maturities of marketable securities	84,390	100,453
Restricted cash	(909)
Net cash provided by investing activities	68,514	9,001
Financing activities
Proceeds from indebtedness to Roche	30,000
Proceeds from stock option exercises	3,805	522
Net cash provided by financing activities	33,805	522
Net increase (decrease) in cash and cash equivalents	13,188	(39,916)
Effect of exchange rate changes on cash and cash equivalents	9
Cash and cash equivalents at beginning of period	63,617	117,763
Cash and cash equivalents at end of period	76,814	77,847
Supplemental disclosure of non-cash investing and financing activities
Cash paid for interest	225	331
Acquisition of property and equipment included in accounts payable and accrued expenses	$ 2,843	$ 5,052