ACQUISITIONS (Schedule of Preliminary Valuation of Assets Acquired and Liabilities Assumed) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 03, 2013 Powwownow	Sep. 04, 2013 ACT
Business Acquisition [Line Items]
Cash and equivalents				$ 1,295	$ 11,137
Other current assets				3,221	11,447
Property and equipment				889	2,861
Intangible assets				35,568	31,000
Deferred income taxes, net				0	1,708
Other assets				8,163	2,854
Total assets acquired				49,136	61,007
Current liabilities				4,551	13,460
Long-Term Liabilities				12,831	4,059
Deferred income taxes, net				6,136	8,452
Total liabilities assumed				23,518	25,971
Total identifiable net assets				25,618	35,036
Goodwill	341,382	297,773	295,690	26,947	16,449
Total net assets				$ 52,565	$ 51,485