Consolidated Balance Sheets - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets, Current [Abstract]
Cash and cash equivalents	$ 126,263	$ 36,112
Short-term investments	26,012	235,547
Accounts receivable, net of allowances of $4	395	56,532
Inventory	0	4,243
Prepaid expenses and other current assets	5,049	5,320
Total current assets	157,719	337,754
Property and equipment, net of accumulated depreciation and amortization of $61,741 and $60,006, respectively	295	14,047
Goodwill	44,543	44,543
Intangible assets, net	0	19,716
Other assets	1,231	1,655
Total assets	203,788	417,715
Liabilities, Current [Abstract]
Accounts payable	5,469	12,178
Accrued liabilities	29,691	42,151
Current portion of long-term debt, net of deferred financing costs	11,646	11,012
Total current liabilities	46,806	65,341
Long-term debt, net of deferred financing costs	0	234,171
Other long-term liabilities	611	1,102
Total liabilities	47,417	300,614
Commitments and contingencies
Stockholders' 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; 106,679 and 106,162 shares issued, respectively	142	106
Additional paid-in capital	1,561,096	1,462,172
Accumulated deficit	(1,400,018)	(1,341,444)
Accumulated other comprehensive income (loss)	(6)	84
Treasury stock, at cost, 407 and 236 shares, respectively	(4,843)	(3,817)
Total stockholders' equity	156,371	117,101
Total liabilities and equity	$ 203,788	$ 417,715
Preferred stock, par value per share (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share (usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized	225,000	225,000