Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net loss	$ (102,888)	$ (66,329)
Adjustments to reconcile net loss to net cash used by operating activities
Share-based compensation	53,168	47,899
Depreciation and amortization	19,045	16,393
Amortization of premiums, accretion of discounts, and (gains) losses on debt securities	(1,384)	653
Gains on equity securities	(62,882)	0
Gain on Immunomedics warrant derivative	0	(76,699)
Income tax benefit on unrealized loss on available-for-sale securities	0	(5,415)
Deferred income taxes	0	(5,672)
Other long-term liabilities	1,035	(102)
Changes in operating assets and liabilities
Accounts receivable, net	(51,472)	(28,504)
Inventories	(15,194)	7,287
Prepaid expenses and other assets	4,183	(2,084)
Accounts payable and accrued liabilities	2,152	6,208
Deferred revenue	(25,014)	(10,141)
Net cash used by operating activities	(179,251)	(116,506)
Investing activities:
Purchases of securities	(374,356)	(445,659)
Proceeds from maturities of securities	270,721	538,200
Proceeds from sales of securities	140,352	60,056
Purchases of property and equipment	(14,941)	(42,615)
Acquisition of Cascadian Therapeutics, Inc., net of cash acquired	(598,151)	0
Net cash provided (used) by investing activities	(576,375)	109,982
Financing activities:
Net proceeds from issuance of common stock	658,242	0
Proceeds from exercise of stock options and employee stock purchase plan	51,896	25,991
Net cash provided by financing activities	710,138	25,991
Net increase (decrease) in cash and cash equivalents	(45,488)	19,467
Cash and cash equivalents at beginning of period	160,945	108,673
Cash and cash equivalents at end of period	$ 115,457	$ 128,140