Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net loss	$ (19,215)	$ (5,013)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	3,780	4,112
Share-based compensation expense	2,751	2,852
Deferred income taxes	(11,099)	(4,440)
Other	8	931
Cash provided (used) due to changes in operating assets and liabilities:
Accounts and other receivables	143,992	63,411
Long-term investment in sales-type lease, net	2,043	2,461
Inventory	(25,844)	(10,944)
Prepaid expenses and other assets	4,093	1,878
Accounts payable	(14,525)	17,762
Accrued payroll and related expenses and other liabilities	(6,057)	(30,542)
Deferred revenue	(10,005)	(8,869)
Net cash provided by operating activities	69,922	33,599
Investing activities:
Sales/maturities of available-for-sale investments	0	5,020
Purchases of available-for-sale investments	(84,878)	(14,962)
Change in restricted cash	(402)	1,616
Purchases of property and equipment	(10,289)	(951)
Net cash used in investing activities	(95,569)	(9,277)
Financing activities:
Proceeds from issuance of common stock through employee stock purchase plan	181	191
Purchase of employee restricted shares to fund related statutory tax withholding	(162)	(80)
Proceeds from exercises of stock options	76	1,491
Net cash provided by financing activities	95	1,602
Effect of foreign exchange rate changes on cash and cash equivalents	910	1,446
Net increase (decrease) in cash and cash equivalents	(24,642)	27,370
Cash and cash equivalents:
Beginning of period	222,962	266,660
End of period	198,320	294,030
Supplemental disclosure of cash flow information:
Cash paid for income taxes	629	835
Non-cash investing and financing activities:
Inventory transfers to fixed assets and service spares	$ 491	$ 2,339