SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) (USD $)	12 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 Investment In Cloud Solutions Provider	Dec. 31, 2013 Convertible Investment In Marketplace	Sep. 30, 2012 Convertible Investment In Marketplace	Dec. 31, 2013 Investment In Conferencing Company	Jun. 30, 2011 Investment In Conferencing Company	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Dec. 31, 2013 Furniture and fixtures Minimum	Dec. 31, 2013 Furniture and fixtures Maximum	Dec. 31, 2013 Capitalized software Minimum	Dec. 31, 2013 Capitalized software Maximum	Dec. 31, 2013 Computer, communication and network equipment Minimum	Dec. 31, 2013 Computer, communication and network equipment Maximum	Dec. 31, 2013 Software Development Maximum	Dec. 31, 2013 North America	Dec. 31, 2012 North America	Dec. 31, 2011 North America
Significant Accounting Policies [Line Items]
Restricted cash	$ 0	$ 600,000
Unbilled revenue within accounts receivable	5,700,000	6,700,000
Billing period lag (in days)	30 days
Provision for doubtful accounts	514,000	1,089,000	626,000
Write-offs of doubtful accounts	600,000	900,000	900,000
Accounts receivable, allowance for doubtful accounts	800,000	800,000	600,000
Tangible assets estimated useful life (in years)											5 years	7 years			3 years	5 years
Finite lived intangible assets useful life (in years)									1 year	20 years			2 years	5 years			5 years
Capitalized Computer Software, Additions	17,500,000	15,300,000	15,300,000
Capitalized software depreciation expense	13,700,000	12,100,000	10,200,000
Percentage by which fair value exceeds carrying value of assets																		20.00%
Asset impairments	1,196,000	879,000	456,000															238,000	861,000	440,000
Investment accounted for under cost method investment	2,100,000	1,900,000		1,000,000		1,000,000		1,000,000
Interest earned on cost method investment (as a percent)					8.00%
USF charges	27,100,000	32,000,000	30,400,000
Shares repurchased (in shares)	100,000	3,200,000
Repurchase and retirement of common stock, value	1,381,000	27,892,000	22,066,000
Average price per share paid for stock repurchase	$ 10.54	$ 8.81
Shares withheld in satisfaction of employee tax withholding obligations	215,387	246,735
Payments related to tax withholding for share-based compensation	2,700,000	2,000,000
Preferred stock, shares authorized	5,000,000.0
Preferred stock, par or stated value per share	$ 0.01
Advertising and promotion costs	6,100,000	8,900,000	16,900,000
Prepaid Advertising	0	300,000
Available-for-sale securities	$ 3,537,000	$ 0					$ 3,500,000