CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 148,348	$ 142,998
Short-term investments	546,706	585,834
Contracts receivable	26,934	3,903
Inventories	6,839	6,290
Investment in Regulus Therapeutics Inc.	93,446	81,881
Other current assets	13,154	15,691
Total current assets	835,427	836,597
Property, plant and equipment, net	89,047	88,958
Licenses, net	2,221	2,690
Patents, net	17,915	17,186
Deposits and other assets	10,823	10,378
Total assets	955,433	955,809
Current liabilities:
Accounts payable	16,487	17,984
Accrued compensation	5,411	12,302
Accrued liabilities	23,746	30,451
Current portion of long-term obligations	2,058	2,882
Current portion of deferred contract revenue	52,586	51,713
Total current liabilities	100,288	115,332
Long-term deferred contract revenue	119,083	127,797
Long-term obligations, less current portion	7,510	7,669
Long-term financing liability for leased facility	71,848	71,731
Total liabilities	679,582	698,029
Stockholders' equity:
Common stock, $0.001 par value; 300,000,000 shares authorized, 119,602,322 and 118,442,726 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	120	118
Additional paid-in capital	1,251,928	1,224,509
Accumulated other comprehensive income	47,114	39,747
Accumulated deficit	(1,023,311)	(1,006,594)
Total stockholders' equity	275,851	257,780
Total liabilities and stockholders' equity	955,433	955,809
1 Percent Convertible Senior Notes [Member]
Current liabilities:
Convertible senior notes	332,274	327,486
2 3/4 Percent Convertible Senior Notes [Member]
Current liabilities:
Convertible senior notes	$ 48,579	$ 48,014