CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities:
Net income (loss)	$ 18,931	$ (43,361)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation	3,406	3,141
Amortization of patents	648	543
Amortization of licenses	937	941
Amortization of premium on investments, net	3,377	3,847
Amortization of debt issuance costs	555	272
Amortization of long-term financing liability for leased facility	3,327	3,306
Stock-based compensation expense	26,910	14,777
Gain on investments, net	(1)	(137)
Non-cash losses related to patents, licensing and property, plant and equipment	166	325
Tax benefit from other unrealized gains on securities	0	(1,395)
Changes in operating assets and liabilities:
Contracts receivable	639	(30,839)
Inventories	(492)	257
Other current and long-term assets	(14,628)	(695)
Accounts payable	(8,197)	1,991
Accrued compensation	(4,387)	(5,738)
Deferred rent	167	69
Accrued liabilities	(6,698)	1,965
Deferred contract revenue	(13,097)	(18,978)
Net cash provided by (used in) operating activities	22,381	(66,343)
Investing activities:
Purchases of short-term investments	(240,570)	(179,196)
Proceeds from the sale of short-term investments	187,522	175,777
Purchases of property, plant and equipment	(3,940)	(3,100)
Acquisition of licenses and other assets, net	(1,749)	(1,791)
Proceeds from the sale of strategic investments	0	737
Net cash used in investing activities	(58,737)	(7,573)
Financing activities:
Proceeds from equity awards	18,035	13,416
Principal payments on debt and capital lease obligations	(5,190)	(5,392)
Net cash provided by financing activities	12,845	8,024
Net decrease in cash and cash equivalents	(23,511)	(65,892)
Cash and cash equivalents at beginning of period	142,998	159,973
Cash and cash equivalents at end of period	119,487	94,081
Supplemental disclosures of cash flow information:
Interest paid	3,377	2,920
Supplemental disclosures of non-cash investing and financing activities:
Amounts accrued for capital and patent expenditures	1,166	453
2 3/4 Percent Convertible Senior Notes [Member]
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of convertible notes discount	1,146	3,366
1 Percent Convertible Senior Notes [Member]
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of convertible notes discount	$ 9,672	$ 0