CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Statement of Cash Flows [Abstract]
Restricted Cash, Current	$ 342
Cash flows from operating activities:
Net Income (Loss)	(63,556)	$ (51,046)
Adjustments to reconcile net loss to net cash provided by operating activities:
Stock-based compensation	14,269	9,402
Depreciation	9,932	5,529
Amortization of intangible assets	9,910	19,269
Non-cash interest expense and amortization of convertible debt issuance costs	3,379	5,396
Impairment of Long-Lived Assets to be Disposed of	16,990	0
Deferred income taxes	266	10,202
Restructuring Costs	0	670
Gain (Loss) on Sale of Equity Investments	175	0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	(291)
Gain from sale of assets held for sale	0	(1,266)
Loss from disposal of property, plant and equipment	(153)	(47)
Change in operating assets and liabilities, net of impact of acquisitions:
Accounts receivable	19,028	(13,665)
Unbilled Receivables	75,328	67,905
Prepaid expenses and other assets	4,636	(2,615)
Inventories	(2,593)	(1,040)
Accounts payable	1,080	(798)
Accrued salaries and benefits and other liabilities	(773)	4,780
Increase (Decrease) in Income Taxes Payable	6,966	5,204
Deferred revenue	8,740	6,441
Increase (decrease) in operating lease liabilities	(4,526)	0
Net cash provided by operating activities	67,460	20,430
Cash flows from investing activities:
Purchases of property, plant and equipment	(2,783)	(5,287)
Purchases of marketable securities	(277,706)	(79,207)
Maturities of marketable securities	216,382	131,823
Proceeds from sale of equity security	0	1,350
Proceeds from sale of assets held for sale	0	3,754
Investment in privately-held company	(1,000)	0
Proceeds from sale of property, plant and equipment	0	10
Net cash provided by (used in) investing activities	(65,107)	52,443
Cash flows from financing activities:
Proceeds received from issuance of common stock under employee stock plans	10,219	5,850
Principal payments against lease financing obligation	0	(499)
Payments Related to Tax Withholding for Share-based Compensation	(4,271)	(5,195)
Payments under Installment	(2,480)	0
Payments for Repurchase of Common Stock	0	(50,031)
Net cash provided by (used in) financing activities	3,468	(49,875)
Effect of exchange rate changes on cash and cash equivalents	0	(558)
Less: net decrease in cash classified within assets held for sale	(7,545)	0
Net increase (decrease) in cash, cash equivalents and restricted cash	1,724	22,440
Cash, cash equivalents and restricted cash at beginning of period	116,252	225,844
Cash, cash equivalents and restricted cash at end of period	114,528	248,284
Non-cash investing and financing activities during the period:
Property, plant and equipment received and accrued in accounts payable and other liabilities	$ 26,762	$ 1,793