Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income	$ 4,057	$ 19,486
Adjustment to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	2,289	1,302
Amortization of software licenses	1,047	910
Stock-based compensation expense	6,972	3,003
Provision for doubtful accounts	326	17
Provision for (benefit from) deferred income taxes	2,801	(9,926)
Tax windfall benefits from (provision for) stock option exercises		77
Non-cash interest expense on convertible senior notes	2,515	172
Other		(8)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	6,884	6,424
Other current and long-term assets	(7,725)	(699)
Accounts payable, accrued expenses and other long-term liabilities	(2,591)	(3,883)
Current and long-term deferred revenue	(8,342)	(4,885)
Net cash provided by operating activities	8,233	11,990
Cash flows from investing activities:
Purchases of property and equipment	(1,660)	(879)
Payments for acquisitions, net of cash acquired	(3,219)
Purchases of marketable securities	(56,675)	(31,482)
Proceeds from sale of marketable securities	12,251	13,271
Proceeds from maturities of marketable securities	32,200
Change in restricted cash		35
Net cash used in investing activities	(17,103)	(19,055)
Cash flows from financing activities:
Proceeds from issuance of convertible senior notes, net of issuance costs		115,688
Proceeds from the exercise of stock options	1,139	3,195
Taxes paid on vesting of RSUs	(1,614)	(380)
Notes payable and bank loans - payments	(429)	(776)
Net cash (used in) provided by financing activities	(904)	117,727
Effect of exchange rate changes on cash and cash equivalents	(45)	68
Net (decrease) increase in cash and cash equivalents	(9,819)	110,730
Cash and cash equivalents, beginning of period	94,072	47,254
Cash and cash equivalents, end of period	$ 84,253	$ 157,984