CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income (loss)	$ 207,630	$ 11,254
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	27,326	26,925
Stock-based compensation	81,207	72,829
Other, net	227	172
Unrealized (gain) loss on long term investments	(16,364)	11,962
Change in fair value of acquisition-related contingent consideration	13,279	13,988
Changes in operating assets and liabilities:
Accounts receivable	4,918	(50,011)
Prepaid expenses and other assets	8,354	(23,589)
Inventory	(2,288)	1,878
Accounts payable	(32,243)	7,888
Accrued and other liabilities	16,577	(20,055)
Net cash provided by operating activities	308,623	53,241
Cash flows from investing activities:
Purchase of long term investments		(8,936)
Capital expenditures	(65,561)	(23,381)
Purchases of marketable securities	(103,970)	(58,827)
Sale and maturities of marketable securities	99,821	58,694
Net cash used in investing activities	(69,710)	(32,450)
Cash flows from financing activities:
Proceeds from issuance of common stock under stock plans	30,672	18,043
Payment of finance lease liabilities	(409)
Payment of contingent consideration	(16,766)	(9,886)
Net cash provided by financing activities	13,497	8,157
Effect of exchange rates on cash, cash equivalents, restricted cash and investments	(158)	135
Net increase in cash, cash equivalents, restricted cash and investments	252,252	29,083
Cash, cash equivalents, restricted cash and investments at beginning of period	1,164,986	900,434
Cash, cash equivalents, restricted cash and investments at end of period	1,417,238	929,517
Supplemental Schedule of Cash Flow Information
Interest paid	119	134
Income taxes paid	6,439	1,944
Leased assets obtained in exchange for new operating lease liabilities	2,358
Leased assets obtained in exchange for new finance lease liabilities	$ 29,740
Convertible Senior Notes 0.375 Percent Due 2018
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversions of 0.375% convertible senior notes due 2018		$ 29

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-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(2)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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