CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	$ 77,985	$ (34,159)
Investing activities:
Purchases of short-term investments	(303,862)	(172,581)
Proceeds from the sale of short-term investments	135,130	189,397
Purchases of property, plant and equipment	(1,113)	(1,033)
Acquisition of licenses and other assets, net	(2,721)	(2,779)
Purchases of strategic investments		(40)
Proceeds from sale of strategic investments	2,110
Net cash (used in) provided by investing activities	(170,456)	12,964
Financing activities:
Proceeds from equity awards	56,898	7,789
Proceeds from issuance of 2 3/4 percent convertible senior notes, net of issuance costs		194,689
Principal and premium payment on redemption of the 2 5/8 percent convertible subordinated notes		(163,718)
Net proceeds from public common stock offering	173,292
Proceeds from equipment financing arrangement	2,513	9,100
Principal payments on debt and capital lease obligations	(8,306)	(7,579)
Net cash provided by financing activities	224,397	40,281
Net increase in cash and cash equivalents	131,926	19,086
Cash and cash equivalents at beginning of period	124,482	65,477
Cash and cash equivalents at end of period	256,408	84,563
Supplemental disclosures of cash flow information:
Interest paid	3,079	5,584
Income taxes paid	2
Supplemental disclosures of non-cash investing and financing activities:
Amounts accrued for capital and patent expenditures	$ 835	$ 839