Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 145,686	$ 133,382
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	112,228	86,501
Stock-based compensation	56,792	47,732
Provision for doubtful accounts	464	1,199
Excess tax benefits from stock-based compensation	(19,661)	(9,622)
Provision for deferred income taxes	21,840	0
Amortization of debt discount and issuance costs	6,457	0
Loss from disposal of property and equipment	38	309
Loss on investments	393	0
Change in fair value of contingent consideration	300	0
Gain and other activity related to divestiture of a business	0	(2,281)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(41,254)	(35,203)
Prepaid expenses and other current assets	(12,998)	(16,208)
Accounts payable and accrued expenses	21,459	23,695
Deferred revenue	4,750	6,612
Other current liabilities	1,419	(223)
Other non-current assets and liabilities	(8,666)	(1,605)
Net cash provided by operating activities	289,247	234,288
Cash flows from investing activities:
Cash (paid) received for acquired businesses, net of cash acquired	(386,532)	80
Purchases of property and equipment	(97,992)	(102,222)
Capitalization of internal-use software development costs	(56,533)	(35,127)
Purchases of short- and long-term marketable securities	(863,591)	(309,875)
Proceeds from sales of short- and long-term marketable securities	354,313	77,720
Proceeds from maturities of short- and long-term marketable securities	183,809	209,473
Proceeds from the sale of property and equipment	584	426
Other non-currents assets and liabilities	1,444	(362)
Net cash used in investing activities	(864,498)	(159,887)
Cash flows from financing activities:
Proceeds from the issuance of convertible senior notes, net of issuance costs	678,735	0
Proceeds from the issuance of warrants related to convertible senior notes	77,970	0
Purchase of note hedge related to convertible senior notes	(101,292)	0
Payment of acquired debt and capital leases	(17,862)	0
Proceeds related to the issuance of common stock under stock plans	57,999	28,261
Excess tax benefits from stock-based compensation	19,661	9,622
Employee taxes paid related to net share settlement of stock-based awards	(34,248)	(21,125)
Repurchases of common stock	(187,491)	(82,782)
Net cash provided by (used in) financing activities	493,472	(66,024)
Effects of exchange rate changes on cash and cash equivalents	2,053	(5,501)
Net (decrease) increase in cash and cash equivalents	(79,726)	2,876
Cash and cash equivalents at beginning of period	333,891	201,989
Cash and cash equivalents at end of period	254,165	204,865
Supplemental disclosure of cash flow information:
Cash paid for income taxes	60,360	35,796
Non-cash financing and investing activities:
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	36,146	14,344
Capitalization of stock-based compensation	7,727	6,183
Convertible note receivable received for divestiture of a business	$ 0	$ 18,882