Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income	$ 87,466	$ 98,538
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	95,746	82,467
Stock-based compensation expense	46,545	27,324
Provision for doubtful accounts	284	454
Excess tax benefits from stock-based compensation	(15,049)	(10,850)
(Gain) Loss on investments and disposal of property and equipment, net	(204)	4
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	6,387	456
Prepaid expenses and other current assets	8,972	841
Accounts payable, accrued expenses and other current liabilities	10,141	(5,713)
Deferred revenue	4,141	(2,182)
Accrued restructuring	(2,869)	(32)
Other non-current assets and liabilities	495	9,052
Net cash provided by operating activities	242,055	200,359
Cash flows from investing activities:
Cash paid for acquisition of business, net of cash acquired	(291,638)	(550)
Purchases of property and equipment	(72,620)	(68,525)
Capitalization of internal-use software costs	(26,263)	(20,450)
Purchases of short- and long-term marketable securities	(416,494)	(578,135)
Proceeds from sales of short- and long-term marketable securities	110,161	272,709
Proceeds from maturities of short- and long-term marketable securities	141,424	238,428
Proceeds from the sale of property and equipment	12	88
Decrease in restricted investments held for security deposits	0	221
Net cash used in investing activities	(555,418)	(156,214)
Cash flows from financing activities:
Proceeds from the issuance of common stock under stock option plans and employee stock purchase plans	22,569	12,122
Excess tax benefits from stock-based compensation	15,049	10,850
Employee taxes paid related to net share settlement of equity awards	(24,196)	(3,507)
Repurchases of common stock	(75,126)	(92,613)
Net cash used in financing activities	(61,704)	(73,148)
Effects of exchange rate changes on cash and cash equivalents	(1,134)	2,766
Net decrease in cash and cash equivalents	(376,201)	(26,237)
Cash and cash equivalents at beginning of period	559,197	231,866
Cash and cash equivalents at end of period	182,996	205,629
Supplemental disclosure of cash flow information:
Cash paid for income taxes	35,563	17,898
Non-cash financing and investing activities:
Capitalization of stock-based compensation, net of impairments	$ 4,133	$ 3,465