CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	$ 12,164	$ (9,288)
Investing activities:
Purchases of short-term investments	(144,250)	(116,653)
Proceeds from the sale of short-term investments	96,926	142,681
Purchases of property, plant and equipment	(591)	(864)
Acquisition of licenses and other assets, net	(1,171)	(1,592)
Proceeds from sale of strategic investments	1,938
Net cash (used in) provided by investing activities	(47,148)	23,572
Financing activities:
Proceeds from equity awards	36,879	1,617
Net proceeds from public common stock offering	173,223
Proceeds from equipment financing arrangement	2,513	9,100
Principal payments on debt and capital lease obligations	(5,573)	(4,833)
Net cash provided by financing activities	207,042	5,884
Net increase in cash and cash equivalents	172,058	20,168
Cash and cash equivalents at beginning of period	124,482	65,477
Cash and cash equivalents at end of period	296,540	85,645
Supplemental disclosures of cash flow information:
Interest paid	2,977	2,275
Income taxes paid	2
Supplemental disclosures of non-cash investing and financing activities:
Amounts accrued for capital and patent expenditures	$ 1,055	$ 679