Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net loss	$ (72,911)	$ (95,751)	$ (74,904)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	96,694	82,719	77,855
Stock-based compensation	76,855	63,884	44,833
Gain from sale of an equity investment	(924)	0	0
Loss (gain) on disposal of property and equipment	444	331	(174)
Net unrealized gain on equity investments	(2,201)	(2,441)	0
Impairment of non-marketable equity investment	0	7,000	0
Impairment of intangible assets	0	0	47,014
Deferred income taxes	337	(8,628)	(22,428)
Accretion of convertible debt and amortization of issuance expenses	28,353	26,394	24,574
Amortization of premiums (discount) on marketable securities	(1,118)	(583)	1,040
Other noncash items	(46)	2	(10)
Changes in assets and liabilities:
Accounts receivable	(1,524)	6,722	(17,392)
Inventories	(21,961)	(1,331)	318
Prepaid expenses and other assets	(2,707)	549	2,272
Income tax payable/receivable	279	(1,671)	(638)
Accounts payable	482	1,963	1,655
Accrued expenses	(805)	(4,902)	(554)
Deferred revenue	(1,713)	4,997	(3,195)
Other liabilities	(590)	(1,095)	(2,958)
Net cash provided by operating activities	96,944	78,159	77,308
Cash flows from investing activities
Purchases of property and equipment	(29,518)	(31,713)	(37,437)
Proceeds from disposal of property and equipment	0	145	100
Purchases of marketable securities	(274,246)	(248,038)	(261,247)
Sales of marketable securities	168,426	11,654	85,163
Maturities of marketable securities	203,068	242,825	182,299
Proceeds from sale of equity investments	3,424	2,414	0
Proceeds from sale of discontinued operations	0	0	10,690
Acquisition of business, net of cash acquired	0	0	(1,800)
Purchases of intangible assets	(1,137)	(126)	(2,421)
Purchases of equity investment in private companies	(7,000)	(12,811)	0
Net cash provided by (used in) investing activities	63,017	(35,650)	(24,653)
Cash flows from financing activities
Proceeds from exercise of stock options	2,616	719	2,214
Proceeds from employee stock purchase plan	6,374	5,906	5,776
Minimum tax withholding paid on behalf of employees for net share settlement	(33,596)	(19,118)	(27,673)
Payments of obligations related to purchase of intangible assets	(24,221)	(21,311)	(13,688)
Repayment of long-term loan	0	405	333
Payments of obligations related to equipment financing	(429)	(542)	(1,034)
Net cash used in financing activities	(49,256)	(33,941)	(34,072)
Net increase in cash and cash equivalents	110,705	8,568	18,583
Cash and cash equivalents at beginning of year	172,018	163,450	144,867
Cash and cash equivalents at end of year	282,723	172,018	163,450
Supplemental cash flow information
Income taxes paid (refund received)	(155)	2,155	2,158
Interest paid	6,577	5,818	5,194
Supplemental disclosure of non-cash investing and financing activities
Software license intangible assets	57,406	20,066	2,888
Equity investment acquired as settlement of receivable from a customer	$ 2,500	$ 0	$ 0