Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating Activities:
Net income (loss)	$ 32,486	$ 25,533
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	8,974	8,490
Depreciation and amortization of intangible assets	27,298	19,413
Excess tax benefits from stock-based award activity	(29,801)	(24,596)
Deferred income taxes	(15,621)	(8,209)
Amortization of premium on investments, net	3,095	2,154
Amortization of debt issuance costs	853	841
Accretion of debt discounts	2,753	1,972
Loss on debt extinguishment and modification expense	0	1,593
Loss on derivative instrument	0	5,931
Impairment loss on equity investment in privately-held company	0	3,711
Other	72	608
Cash provided (used) by changes in operating assets and liabilities:
Accounts receivable	16,212	(8,756)
Other receivables	4,134	1,090
Inventories	1,067	900
Prepaid expenses and other current assets	849	6,694
Other long-term assets	43	(2,296)
Accounts payable	(18,382)	1,873
Deferred revenue	(48)	2,563
Accrued expenses and other current and long-term liabilities	17,174	27,176
Net cash provided by operating activities	51,158	66,685
Investing Activities:
Business acquisitions, net of cash acquired	(44,927)	(180,500)
Purchases of property and equipment	(4,247)	(3,066)
Change in restricted cash	0	2,491
Equity investment in privately-held company	0	(4,000)
Proceeds from sales of investments	26,620	25,812
Proceeds from maturities of investments	195,296	150,277
Purchases of investments	(237,063)	(234,771)
Net cash used by investing activities	(64,321)	(243,757)
Financing Activities:
Proceeds from issuance of convertible notes, net of debt issuance costs of $6,432	0	194,818
Proceeds from credit facilities	4,000	0
Repayment of credit facilities	(62,000)	(10,000)
Debt issuance costs on credit facility	0	(28)
Stock repurchases	(29,923)	(3,525)
Excess tax benefits from stock-based award activity	29,801	24,596
Proceeds from stock option exercises	2,447	1,700
Proceeds from issuance of stock through employee stock purchase plan	1,376	1,065
Tax payments from shares withheld upon vesting of restricted stock units	(2,569)	(2,011)
Net cash provided (used) by financing activities	(56,868)	206,615
Net increase (decrease) in cash and cash equivalents	(70,031)	29,543
Cash and cash equivalents, beginning of period	130,225	68,278
Cash and cash equivalents, end of period	60,194	97,821
Supplemental disclosure of non-cash investing activities:
Purchases of property and equipment through leasehold incentives	120	1,006
Cash paid for:
Income taxes	2,536	1,637
Interest	$ 6,336	$ 6,512