CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net loss	$ (5,803)	$ (9,097)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,339	1,422
Amortization of premium/discount on purchased securities	1,369	1,463
Write-off of inventory	502	598
Non-cash equity-based compensation expense	4,221	3,262
Non-cash income tax benefit		(494)
Gains on sale of assets	(865)
(Gains) losses on investments, net	(32)	1,471
Changes in operating assets and liabilities:
Accounts receivable, net	(2,080)	154
Inventories	695	1,678
Receivable from collaboration	(105)	(14,705)
Prepaid and other current assets	555	2,086
Accounts payable and accrued expenses	(6,089)	(6,546)
Deferred revenues	(3,783)	(3,048)
Other long-term liabilities	(227)	(199)
Total adjustments	(4,500)	(12,858)
Net cash used in operating activities	(10,303)	(21,955)
Cash flows from investing activities:
Proceeds from sales or maturities of investments	63,767	85,234
Purchase of investments	(69,653)	(96,178)
Acquisition of MuGard Rights and inventory	(3,434)
Proceeds from sale of assets	977
Change in restricted cash	(400)
Capital expenditures		(47)
Net cash used in investing activities	(8,743)	(10,991)
Cash flows from financing activities:
Proceeds from the exercise of stock options	379
Proceeds from the issuance of common stock under ESPP	176	150
Net cash provided by financing activities	555	150
Net decrease in cash and cash equivalents	(18,491)	(32,796)
Cash and cash equivalents at beginning of the period	46,293	63,474
Cash and cash equivalents at end of the period	$ 27,802	$ 30,678