CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss		$ (64,972)	$ (41,123)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization		39,305	44,986
Stock-based compensation		19,221	21,082
Provision for bad debts		1,152	2,522
Loss on the disposition of property, equipment and other assets		1,620	0
Provision for deferred income taxes		(1,346)	(3,132)
Impairment of assets		1,728	1,411
Changes in operating accounts:
Accounts receivable		12,290	(1,509)
Inventories		6,481	(29,502)
Prepaid expenses and other current assets		(3,122)	41,589
Accounts payable		(12,885)	6,261
Deferred revenue and customer deposits		4,491	(37)
Accrued and other current liabilities		1,199	(45,309)
All other operating activities		4,922	(170)
Net cash provided by (used in) operating activities		10,084	(2,931)
Cash flows from investing activities:
Purchases of property and equipment		(18,265)	(28,323)
Proceeds from sale of assets		1,620	9
Other investing activities		(1,744)	(1,236)
Net cash used in investing activities		(18,389)	(29,550)
Cash flows from financing activities:
Proceeds from borrowings		100,000	0
Repayment of borrowings/long term debt		(66,013)	0
Payments related to net-share settlement of stock based compensation		(3,029)	(5,723)
Purchase of noncontrolling interest		(2,500)	0
Payments on earnout consideration		0	(2,675)
Other financing activities		(1,125)	(508)
Net cash provided by (used in) financing activities		27,333	(8,906)
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(1,400)	(2,417)
Net increase (decrease) in cash, cash equivalents and restricted cash		17,628	(43,804)
Cash, cash equivalents and restricted cash at the beginning of the period	[1]	110,919	136,831
Cash, cash equivalents and restricted cash at the end of the period	[1]	128,547	93,027
Supplemental Cash Flow Information [Abstract]
Cash interest payments		3,020	353
Cash income tax payments, net		8,984	7,119
Transfer of equipment from inventory to property and equipment, net	[2]	2,861	4,638
Transfer of equipment to inventory from property and equipment, net	[3]	30	628
Purchase of noncontrolling interest	[4]	$ (11,000)	$ 0

[1] The amounts for cash and cash equivalents shown above include restricted cash of $931 and $934 as of September 30, 2019 and 2018, respectively, and $921 and $487 as of December 31, 2018, and 2017, respectively, which were included in Other assets, net, in the condensed consolidated balance sheets.

[2] Inventory is transferred from inventory to property and equipment at cost when the Company requires additional machines for training or demonstration or for placement into on demand manufacturing services locations.

[3] In general, an asset is transferred from Property and equipment, net, into inventory at its net book value when the Company has identified a potential sale for a used machine.

[4] Purchase of noncontrolling interest to be paid in installments over a four-year period recorded to Accrued and other liabilities and Other liabilities on the condensed consolidated balance sheets.