Income Taxes (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred tax assets:
Allowance for doubtful accounts and deferred revenue	$ 422,000	$ 883,000
Restructuring cost	142,000	157,000
Goodwill and other intangibles	7,261,000	5,957,000
Accounts receivables	5,043,000	4,308,000
Net operating loss carry forwards	52,000	136,000
Deferred stock compensation	5,311,000	5,588,000
Deferred rent	226,000	454,000
Other	1,410,000	1,483,000
Total deferred tax assets before valuation allowance	19,867,000	18,966,000
Less valuation allowance	(81,000)	(81,000)
Total deferred tax assets after valuation allowance	19,786,000	18,885,000
Deferred tax liabilities:
Goodwill and other intangibles	72,106,000	81,689,000
Capitalized software cost	2,946,000	2,107,000
Property and equipment	7,937,000	7,251,000
Total deferred tax liabilities	82,989,000	91,047,000
Total net deferred tax (liabilities)/assets	(63,203,000)	(72,162,000)
Net deferred tax (liabilities)/assets
Net current deferred tax assets/ (liabilities)	(2,398,000)	2,198,000
Net non-current deferred tax liabilities	(60,805,000)	(74,360,000)
Total net deferred tax (liabilities)/assets	(63,203,000)	(72,162,000)
Tax deductions arising from 2012 stock option exercises utilized	33,000,000
Excess tax benefit from exercise of stock options	12,433,000	12,051,000	12,581,000
Net unrecognized tax benefits	2,000,000	1,300,000
Accrued liabilities for interest and penalties related to uncertain tax positions	800,000	500,000
Reasonably possible decrease in unrecognized tax benefits within the next year	$ 100,000