CONSOLIDATED STATEMENTS OF CASH FLOW - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (1,056)	$ (12,708)
Adjustments to reconcile net loss to net cash used for operating activities:
Depreciation and amortization	252	291
Amortization of debt issuance costs and discounts	4,935	4,535
Amortization of discount or premium on available-for-sale securities	245	253
Share-based compensation expense	727	252
Changes in assets and liabilities:
Accounts receivable	(1,965)	(2,858)
Inventories	(1,004)	2,178
Prepaid expenses and other assets	3,740	4,104
Accounts payable	200	604
Accrued and other liabilities	4,740	(5,644)
Deferred revenue	(17,886)	(2,745)
Net cash used for operating activities	(7,072)	(11,738)
Cash flows from investing activities:
Property and equipment purchases	(21)
Purchases of available-for-sale securities	(20,915)	(30,423)
Proceeds from maturity of available-for-sale securities	12,234	29,000
Proceeds from sale of Available-for-sale Securities	820	3,666
Net cash (used for) provided by investing activities	(7,882)	2,243
Cash flows from financing activities:
Repayments of notes payable	(2,076)	(2,199)
Net cash used for financing activities	(2,076)	(2,199)
Net decrease in cash and cash equivalents	(17,030)	(11,694)
Cash and cash equivalents:
Beginning of period	84,783	95,395
End of period	$ 67,753	$ 83,701