Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities
Net income (loss)	$ (18,530)	$ (15,827)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	8,796	17,726
Non-cash interest expense	3,081	2,859
Deferred income taxes	(15)	(269)
Share-based compensation expense	3,157	4,537
Changes in operating assets and liabilities:
Accounts receivable and contract assets	(8,134)	(11,177)
Inventories and deferred cost of sales	8,489	4,555
Prepaid expenses and other current assets	(2,457)	3,824
Accounts payable and accrued expenses	(12,260)	2,009
Customer deposits and deferred revenue	(3,855)	(17,559)
Income taxes receivable and payable, net	(463)	(2,283)
Other, net	(100)	(202)
Net cash provided by (used in) operating activities	(22,291)	(11,807)
Cash Flows from Investing Activities
Capital expenditures	(2,180)	(2,259)
Proceeds from the sale of investments	22,500	34,000
Payments for purchases of investments	(41,258)	(54,300)
Net cash provided by (used in) investing activities	(20,938)	(22,559)
Cash Flows from Financing Activities
Cash withholdings for employee stock purchase plan	1,021	1,136
Restricted stock tax withholdings	(642)	(427)
Purchases of common stock		(592)
Net cash provided by (used in) financing activities	379	117
Effect of exchange rate changes on cash and cash equivalents	11	32
Net increase (decrease) in cash, cash equivalents, and restricted cash	(42,839)	(34,217)
Cash, cash equivalents, and restricted cash - beginning of period	213,082	280,583
Cash, cash equivalents, and restricted cash - end of period	170,243	246,366
Supplemental Disclosure of Cash Flow Information
Interest paid	4,693	4,674
Income taxes paid	2,341	2,373
Non-cash operating and financing activities
Net transfer of property, plant and equipment to inventory	130	$ 339
Net transfer of inventory to property, plant and equipment	$ 238