CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (18,764)	$ (63,556)
Adjustments to reconcile net loss to net cash provided by operating activities:
Stock-based compensation	12,779	14,269
Depreciation	14,625	9,932
Amortization of intangible assets	9,276	9,910
Non-cash interest expense and amortization of convertible debt issuance costs	3,571	3,379
Impairment of assets held for sale	0	16,990
Deferred income taxes	102	(266)
Loss on equity investment	(318)	(175)
Loss from disposal of property, plant, and equipment	2	153
Change in fair value of earn-out liability	(1,800)	0
Change in operating assets and liabilities, net of impact of acquisitions:
Accounts receivable	8,841	19,028
Unbilled receivables	83,577	75,328
Prepaid expenses and other assets	1,849	4,636
Inventories	(1,468)	(2,593)
Accounts payable	1,709	1,080
Accrued salaries and benefits and other liabilities	(2,030)	(773)
Income taxes payable	(8,643)	(6,966)
Deferred revenue	(1,106)	(8,740)
Operating lease liabilities	(3,565)	(4,526)
Net cash provided by operating activities	99,273	67,460
Cash flows from investing activities:
Purchases of property, plant, and equipment	(12,780)	(2,783)
Purchases of marketable securities	(487,521)	(277,706)
Maturities of marketable securities	407,556	216,382
Proceeds from sale of marketable securities	2,496	0
Settlement of working capital adjustment from disposal of business	(1,131)	0
Investment in privately-held company	0	(1,000)
Net cash used in investing activities	(91,380)	(65,107)
Cash flows from financing activities:
Proceeds received from issuance of common stock under employee stock plans	7,880	10,219
Payments of taxes on restricted stock units	(7,663)	(4,271)
Payments under installment payment arrangement	(6,600)	(2,480)
Net cash provided by (used in) financing activities	(6,383)	3,468
Effect of exchange rate changes on cash and cash equivalents	(419)	0
Less: net decrease in cash classified within assets held for sale	0	(7,545)
Net increase in cash, cash equivalents and restricted cash	1,091	(1,724)
Cash, cash equivalents and restricted cash at beginning of period	102,518	116,252
Cash, cash equivalents and restricted cash at end of period	103,609	114,528
Non-cash investing and financing activities during the period:
Property, plant and equipment received and accrued in accounts payable and other liabilities	$ 26,354	$ 26,762