CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities
Net loss	$ (168,317)	$ (89,871)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Depreciation and amortization	23,156	13,601
Non-cash compensation expense	40,561	26,331
Other non-cash charges and expenses, net	2,121	2,627
Changes in assets and liabilities
Decrease (increase) in accounts receivable	14,665	(16,719)
(Increase) decrease in prepaid expenses and other assets	(6,307)	3,446
(Decrease) increase in deferred revenue	(32,498)	172,660
Increase in accounts payable, accrued expenses, and other liabilities	35,254	27,998
Total adjustments	76,952	229,944
Net cash (used in) provided by operating activities	(91,365)	140,073
Cash flows from investing activities
Purchases of marketable securities	(115,538)	(241,665)
Sales or maturities of marketable securities	324,530	228,483
Capital expenditures	(45,928)	(67,427)
Increase in restricted cash	(685)	(1,800)
Net cash provided by (used in) investing activities	162,379	(82,409)
Cash flows from financing activities
Proceeds in connection with facility lease obligations	0	47,544
Payments in connection with facility lease obligations	(468)	(757)
Net proceeds from the issuance of Common Stock	23,989	13,760
Payments in connection with capital lease obligations	(712)	0
Net cash provided by financing activities	22,809	60,547
Net increase in cash and cash equivalents	93,823	118,211
Cash and cash equivalents at beginning of period	112,572	207,075
Cash and cash equivalents at end of period	$ 206,395	$ 325,286