CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 9,743	$ (8,568)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization of deferred revenue	1,837	1,479
Depreciation	927	734
Amortization of intangibles	29	19
Amortization of premium and discount on investments, net	(437)	(166)
Stock-based employee compensation	1,951	2,151
Stock-based non-employee compensation	0	2
Non-cash expense under a materials agreement	0	9
Stock-based compensation to Board of Directors and Scientific Advisory Board	437	718
Loss on stock warrant liability	0	(4,430)
Retirement plan benefit expense	777	763
Increase (decrease) in assets:
Accounts receivable	(1,147)	(707)
Inventory	4,728	459
Other current assets	2,257	395
Other assets	(10)	107
Increase in liabilities:
Accounts payable and accrued expenses	1,899	1,836
Other current liabilities	205	0
Deferred revenue	1,335	1,645
Net cash provided by operating activities	9,201	1,840
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	2,054	1,510
Purchase of intangibles	18	440
Purchase of investments	177,449	253,904
Proceeds from sale of investments	220,552	45,500
Net cash provided by (used in) investing activities	41,031	(210,354)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from the issuance of common stock	137	249,822
Proceeds from the exercise of common stock options and warrants	943	7,543
Payment of withholding taxes related to stock-based employee compensation	3,508	3,980
Net cash (used in) provided by financing activities	(2,428)	253,385
INCREASE IN CASH AND CASH EQUIVALENTS	47,804	44,871
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	111,795	20,369
CASH AND CASH EQUIVALENTS, END OF PERIOD	159,599	65,240
The following non-cash activities occurred:
Unrealized (loss) gain on available-for-sale securities	(39)	206
Common stock issued to Board of Directors and Scientific Advisory Board that was earned in a previous period	328	300
Common stock issued to employees that was accrued for in a previous period, net of shares withheld for taxes	252	1,113
Fair value of stock warrant liability reclassified to shareholders' equity upon exercise	$ 0	$ 10,501