SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 05, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Jun. 30, 2011
Significant Accounting Policies [Line Items]
Restricted cash		$ 800,000		$ 800,000		$ 400,000
Unbilled revenue within accounts receivable		9,100,000		9,100,000		6,600,000
Provision for doubtful accounts		300,000	100,000	828,000	456,000
Write-offs of doubtful accounts		300,000	300,000	700,000	600,000
Property and equipment, accumulated depreciation		126,600,000		126,600,000		108,800,000
Capitalized software development costs		3,600,000	3,700,000	11,200,000	11,200,000
Capitalized software depreciation expense		3,200,000	2,400,000	9,000,000	7,100,000
Interest earned on cost method investment				8.00%
Investment accounted for under cost method investment		1,000,000		1,000,000			1,000,000
Repurchase and retirement of common stock, shares				1,990,843	2,627,164
Repurchase and retirement of common stock, value				17,672,000	19,400,000
Average price per share paid for stock repurchase	$ 8.66			$ 8.88	$ 7.37
Shares withheld in satisfaction of employee tax withholding obligations				192,883	179,141
Payments Related to Tax Withholding for Share-based Compensation				1,700,000	1,500,000
Preferred stock, shares authorized		5,000,000		5,000,000
Preferred stock, par or stated value per share		$ 0.01		$ 0.01
Income tax expense		855,000	2,047,000	6,618,000	5,789,000
Tax benefit		800,000
Unrecognized tax benefits		3,800,000		3,800,000		3,400,000
Unrecognized tax benefits that would affect effective tax rate, if recognized		2,500,000		2,500,000		2,500,000
Reserve for Sales and Excise Tax [Member]
Significant Accounting Policies [Line Items]
Valuation allowances and reserves		2,100,000		2,100,000		1,700,000
Foreign and State Net Operating Loss and Capital Loss Carryforwards [Member]
Significant Accounting Policies [Line Items]
Increase in valuation allowance				400,000
Accumulated Other Comprehensive Income (Loss) [Member]
Significant Accounting Policies [Line Items]
Repurchase and retirement of common stock, value
Minimum [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets useful life				1 year
Maximum [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets useful life				20 years
Furniture and Fixtures [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Tangible assets estimated useful life				5 years
Furniture and Fixtures [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Tangible assets estimated useful life				7 years
Software [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets useful life				2 years
Software [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets useful life				5 years
Computer, communication and network equipment [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Tangible assets estimated useful life				3 years
Computer, communication and network equipment [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Tangible assets estimated useful life				10 years