Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 20,421	$ 61,661
Short-term investments	241,851	249,127
Accounts receivable, net of allowances of $4	4,482	4,825
Inventory	2,112	1,948
Prepaid expenses and other current assets	4,284	4,434
Total current assets	273,150	321,995
Property and equipment, net of accumulated depreciation and amortization of $59,067 and $58,623, respectively	17,244	17,687
Goodwill	44,543	44,543
Other intangible assets, net of accumulated amortization of $1,912 and $1,471, respectively	51,444	51,885
Other assets	432	429
Total assets	386,813	436,539
Current liabilities:
Accounts payable	66,553	57,652
Accrued liabilities	12,863	12,282
Current portion of deferred revenue	7,437	40,099
Current portion of long-term debt, net of deferred issuance costs	13,517	14,094
Total current liabilities	100,370	124,127
Deferred revenue, net of current portion	22,077	22,428
Long-term debt, net of deferred issuance costs	231,879	231,576
Deferred tax liabilities	6,014	6,014
Other long-term liabilities	279	292
Total liabilities	360,619	384,437
Commitments and contingencies
Equity:
Preferred stock, $.01 par value; 5,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $.001 par value; 225,000 shares authorized; 106,048 and 105,711 shares issued, respectively	106	106
Additional paid-in capital	1,438,625	1,435,526
Accumulated deficit	(1,409,267)	(1,381,404)
Accumulated other comprehensive loss	(394)	(222)
Treasury stock, at cost, 236 and 122 shares, respectively	(2,876)	(1,904)
Total equity	26,194	52,102
Total liabilities and equity	$ 386,813	$ 436,539