Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows from Operating Activities
Net income (loss)	$ (8,869)	$ (34,095)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	15,372	17,315
Non-cash interest expense	6,778	6,219
Deferred income taxes	191	10
Share-based compensation expense	6,620	7,745
Loss on extinguishment of debt	3,046
Asset impairment	281
Changes in operating assets and liabilities:
Accounts receivable and contract assets	(9,454)	6,227
Inventories and deferred cost of sales	(4,520)	8,534
Prepaid expenses and other current assets	(3,578)	(3,957)
Accounts payable and accrued expenses	5,820	(25,955)
Customer deposits and deferred revenue	3,470	11,294
Income taxes receivable and payable, net	93	(587)
Other, net	2,300	(891)
Net cash provided by (used in) operating activities	17,550	(8,141)
Cash Flows from Investing Activities
Capital expenditures	(1,957)	(6,441)
Proceeds from the sale of investments	103,630	40,500
Payments for purchases of investments	(100,265)	(76,108)
Proceeds from held for sale assets, net of costs to sell	9,503
Net cash provided by (used in) investing activities	10,911	(42,049)
Cash Flows from Financing Activities
Proceeds from issuance of 2027 Notes, net of issuance costs	121,946
Purchase of capped calls	(10,313)
Repurchase of 2023 Notes	(81,240)
Proceeds (net of tax withholdings) from option exercises and employee stock purchase plan	1,592	1,784
Restricted stock tax withholdings	(1,518)	(2,241)
Net cash provided by (used in) financing activities	30,467	(457)
Effect of exchange rate changes on cash and cash equivalents	(29)	13
Net increase (decrease) in cash, cash equivalents, and restricted cash	58,899	(50,634)
Cash, cash equivalents, and restricted cash - beginning of period	129,951	213,082
Cash, cash equivalents, and restricted cash - end of period	188,850	162,448
Supplemental Disclosure of Cash Flow Information
Interest paid	5,508	4,721
Income taxes paid	66	2,618
Non-cash operating and financing activities
Net transfer of property, plant and equipment to inventory	526	3,695
Right-of-use assets obtained in exchange for lease obligations	$ 913	$ 339