Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 135,697	$ 140,823
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	149,203	124,228
Stock-based compensation expense	69,180	42,465
Provision for doubtful accounts	(61)	1,236
Excess tax benefits from stock-based compensation	(17,589)	(11,460)
Provision for deferred income taxes, net	826	20,906
(Gain) on investments and disposal of property and equipment, net	(62)	(172)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(21,587)	(7,821)
Prepaid expenses and other current assets	11,103	(78)
Accounts payable, accrued expenses and other current liabilities	54,732	(5,268)
Deferred revenue	5,542	(1,386)
Accrued restructuring	(2,897)	(180)
Other non-current assets and liabilities	(536)	13,355
Net cash provided by operating activities	383,551	316,648
Cash flows from investing activities:
Cash paid for acquisition of business, net of cash acquired	(306,030)	(550)
Purchases of property and equipment	(119,256)	(105,769)
Capitalization of internal-use software costs	(39,921)	(30,523)
Purchases of short- and long-term marketable securities	(554,303)	(727,453)
Proceeds from sales of short- and long-term marketable securities	135,993	545,568
Proceeds from maturities of short- and long-term marketable securities	214,159	354,552
Proceeds from the sale of property and equipment	12	135
Decrease in restricted investments held for security deposits	0	221
Net cash (used in) provided by investing activities	(669,346)	36,181
Cash flows from financing activities:
Proceeds from the issuance of common stock under stock option plans and employee stock purchase plans	28,635	13,305
Excess tax benefits from stock-based compensation	17,589	11,460
Employee taxes paid related to net share settlement of equity awards	(26,566)	(5,680)
Repurchases of common stock	(111,649)	(247,738)
Net cash used in financing activities	(91,991)	(228,653)
Effects of exchange rate changes on cash and cash equivalents	1,239	(443)
Net (decrease) increase in cash and cash equivalents	(376,547)	123,733
Cash and cash equivalents at beginning of period	559,197	231,866
Cash and cash equivalents at end of period	182,650	355,599
Supplemental disclosure of cash flow information:
Cash paid for income taxes	51,822	26,530
Non-cash financing and investing activities:
Capitalization of stock-based compensation, net of impairments	$ 6,694	$ 5,406