Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 133,382	$ 87,466
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	86,501	95,746
Stock-based compensation	47,732	46,545
Provision for doubtful accounts	1,199	284
Loss (gain) on disposal of property and equipment, net	309	(204)
Excess tax benefits from stock-based compensation	(9,622)	(15,049)
Gain on divestiture of a business	(1,188)	0
Unrealized gain on convertible note receivable	(1,093)	0
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(35,203)	6,387
Prepaid expenses and other current assets	(19,106)	8,972
Accounts payable, accrued expenses and other current liabilities	25,311	10,141
Deferred revenue	6,612	4,141
Accrued restructuring	(223)	(2,869)
Other non-current assets and liabilities	(1,849)	495
Net cash provided by operating activities	232,762	242,055
Cash flows from investing activities:
Cash received (paid) for acquired businesses, net of cash acquired	80	(291,638)
Purchases of property and equipment	(100,847)	(72,620)
Capitalization of internal-use software costs	(35,127)	(26,263)
Purchases of short- and long-term marketable securities	(309,875)	(416,494)
Proceeds from sales of short- and long-term marketable securities	77,720	110,161
Proceeds from maturities of short- and long-term marketable securities	209,473	141,424
Proceeds from the sale of property and equipment	426	12
Net cash used in investing activities	(158,150)	(555,418)
Cash flows from financing activities:
Proceeds from the issuance of common stock under stock option plans	28,050	22,569
Excess tax benefits from stock-based compensation	9,622	15,049
Employee taxes paid related to net share settlement of stock-based awards	(21,125)	(24,196)
Repurchases of common stock	(82,782)	(75,126)
Net cash used in financing activities	(66,235)	(61,704)
Effects of exchange rate changes on cash and cash equivalents	(5,501)	(1,134)
Net increase (decrease) in cash and cash equivalents	2,876	(376,201)
Cash and cash equivalents at beginning of period	201,989	559,197
Cash and cash equivalents at end of period	204,865	182,996
Supplemental disclosure of cash flow information:
Cash paid for income taxes	35,796	35,563
Non-cash financing and investing activities:
Purchases of property and equipment included in accrued expenses	14,344	13,103
Capitalization of stock-based compensation, net of impairments	6,183	4,133
Convertible note receivable received for divestiture of a business	$ 18,882	$ 0