FINANCIAL INFORMATION Financial Information (Details) - USD ($) $ in Thousands		3 Months Ended
	Apr. 08, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 104,550
Inventory, Net			$ 34,328	$ 32,956
Assets			299,670	265,843
Accounts receivable, net of allowances of $1,339 and $1,339 at March 31, 2019 and December 31, 2018, respectively			61,318	67,754
Long-term deferred revenues			13,361	13,939
Liabilities			466,757	432,504
Deferred Revenue, Current			87,927	85,662
Accumulated deficit			(1,187,223)	(1,187,010)
Stockholders' Equity Attributable to Parent			$ (167,087)	$ (166,661)
Subsequent Event [Member] | Cerberus Business Finance LLC [Member]
Debt Instrument, Description	On April 8, 2019, we entered into an amendment to our existing agreement (the “Financing Agreement”) with Cerberus Business Finance, LLC, as collateral and administrative agent, and the lenders party thereto. The amendment provides for an additional delayed draw term loan commitment in the aggregate principal amount of $100 million (the “Delayed Draw Funds”), which may be used to fund the purchase of our 2.00% Senior Convertible Notes due 2020 (the “Notes”). On May 2, 2019, we received the Delayed Draw Funds under the Financing Agreement. The Delayed Draw Funds will remain available to us to purchase Notes for a period of 90 calendar days. At the end of such 90-day period, any remaining Delayed Draw Funds that have not been used to purchase Notes must be repaid and no further funds will be available to borrow under the commitment. Any Delayed Draw Funds drawn and used to fund the purchase of the Notes will mature on May 10, 2023, the current maturity date under the Financing Agreement. Under the terms of the amendment, interest accrues on the Delay Draw Funds and the existing outstanding borrowings under the Financing Agreement at a rate of either the LIBOR Rate (as defined in the Financing Agreement) plus 6.25% or a Reference Rate (as defined in the Financing Agreement) plus 5.25%, at our option.