ACQUISITIONS (Schedule of Valuation of Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Oct. 16, 2014	Sep. 19, 2014
Business Acquisition [Line Items]
Goodwill	$ 417,699	$ 386,416
Central Desktop
Business Acquisition [Line Items]
Cash and equivalents			$ 193
Other current assets			902
Property and equipment			301
Intangible assets			9,200
Deferred income taxes, net			905
Other assets			64
Total assets acquired			11,565
Current liabilities			5,723
Long-term liabilities			0
Deferred income taxes, net			3,492
Total liabilities assumed			9,215
Total identifiable net assets			2,350
Goodwill			22,726
Total net assets			$ 25,076
TalkPoint
Business Acquisition [Line Items]
Cash and equivalents				$ 2
Other current assets				3,340
Property and equipment				303
Intangible assets				28,400
Deferred income taxes, net				0
Other assets				1,578
Total assets acquired				33,623
Current liabilities				1,442
Long-term liabilities				8,006
Deferred income taxes, net				0
Total liabilities assumed				9,448
Total identifiable net assets				24,175
Goodwill				31,652
Total net assets				$ 55,827