CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ (199,567)		$ 58,472
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	27,379		23,908
Stock-based compensation	64,358		42,071
Expense related to senior note conversions	54,881
Other, net	146		251
Unrealized loss on long term investment	25,388		3,804
Change in fair value of acquisition-related contingent consideration	14,429		2,271
Changes in operating assets and liabilities:
Accounts receivable	(20,758)		(2,818)
Prepaid expenses and other assets	(33,492)		(7,460)
Inventory	4,462		1,682
Accounts payable	(6,506)		8,883
Accrued and other liabilities	12,436		(9,528)
Deferred revenue-collaborative agreements			(6,429)
Net cash provided by (used in) operating activities	(56,844)		115,107
Cash flows from investing activities:
Acquisition of business, net of cash acquired			(144,845)
Purchase of long term investments	(123,891)
Capital expenditures	(51,466)		(87,776)
Purchases of marketable securities	(115,254)		(17,795)
Sale and maturities of marketable securities	114,474		63,892
Net cash used in investing activities	(176,137)		(186,524)
Cash flows from financing activities:
Restricted investments, net	(57)		13,987
Proceeds from issuance of common stock under stock plans	49,461		24,105
Cash paid in connection with senior note conversions	(8,934)
Direct financing arrangements repayments			(445)
Payment of contingent consideration	(8,035)
Net cash provided by financing activities	32,435		37,647
Effect of exchange rates on cash and cash equivalents	(43)		(15)
Net decrease in cash and cash equivalents	(200,589)		(33,785)
Cash and cash equivalents at beginning of period	652,343	[1]	521,439
Cash and cash equivalents at end of period	451,754		487,654
Supplemental Schedule of Cash Flow Information
Interest paid	180		3,892
Income taxes paid	5,561		229
Unpaid purchases of property and equipment	10,866		6,570
0.375% Convertible Senior Notes due 2018
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Expense related to senior note conversions	1,400
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversions or exchange of convertible senior notes	351,034
1.25% Convertible Senior Notes due 2020
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Expense related to senior note conversions	5,100
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversions or exchange of convertible senior notes	$ 330,010		$ 4

[1] The condensed consolidated balance sheet at December 31, 2016 has been derived from the audited financial statements at that date.