Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities:
Net income	$ 12,711,000	$ 14,107,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,459,000	961,000
Stock-based compensation expense	6,259,000	4,942,000
Impairment of deferred costs	1,892,000
Amortization of acquired intangible assets	31,000	56,000
Deferred taxes	2,985,000	4,220,000
Gain on disposal of property and equipment	(93,000)	(9,000)
Purchases of treasury stock in connection with tax withholdings on restricted stock grants	(855,000)	(395,000)
Reversal of allowance for doubtful accounts	(81,000)	(82,000)
Unrealized gain on foreign currency forward contract	41,000
Tax benefit related to stock-based compensation expense	1,235,000	454,000
Excess tax benefit from stock-based compensation	(1,154,000)	(439,000)
Changes in operating assets and liabilities:
Accounts receivable	7,877,000	6,021,000
Prepaid expenses and other assets	(1,132,000)	(1,106,000)
Accounts payable	(768,000)	(1,261,000)
Accrued compensation and related benefits	(2,413,000)	(3,972,000)
Accrued and other liabilities	(334,000)	(1,293,000)
Deferred revenues	501,000	(796,000)
Billings in excess of recognized revenues	(343,000)	(521,000)
Net cash provided by operating activities	27,818,000	20,887,000
Investing activities:
Purchases of property and equipment	(3,274,000)	(3,372,000)
Proceeds from the sales of property and equipment	135,000
Net cash used in investing activities	(3,139,000)	(3,372,000)
Financing activities:
Proceeds from exercise of stock options	3,062,000	4,270,000
Proceeds from employee stock purchase plan	1,437,000	1,317,000
Excess tax benefit from stock-based compensation	1,154,000	439,000
Purchases of treasury stock	(3,566,000)
Net cash provided by financing activities	2,087,000	6,026,000
Effect of exchange rate changes on cash and cash equivalents	(16,000)	55,000
Net change in cash and cash equivalents	26,750,000	23,596,000
Cash and cash equivalents, beginning of period	89,371,000	61,637,000
Cash and cash equivalents, end of period	116,121,000	85,233,000
Cash paid during the period for:
Taxes	3,322,000	3,252,000
Property and equipment received and accrued in accounts payable and accrued and other liabilities	$ 170,000	$ 347,000