FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS (Details 2)	12 Months Ended					12 Months Ended					12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 Twoo [Member] USD ($)	Dec. 31, 2014 Twoo [Member] EUR (€)	Dec. 31, 2014 Auction rate securities USD ($)	Dec. 31, 2013 Auction rate securities USD ($)	Dec. 31, 2014 Contingent Consideration Arrangement USD ($)	Dec. 31, 2013 Contingent Consideration Arrangement USD ($)	Dec. 31, 2014 Contingent Consideration Without Limit USD ($)	Dec. 31, 2014 Contingent Consideration Liability - Twoo
Changes in assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance at the beginning of the period, assets						$ 8,920,000	$ 8,100,000
Included in other comprehensive (loss) income, assets						(2,850,000)	820,000
Settlements, assets							0
Balance at the end of the period, assets						6,070,000	8,920,000
Changes in liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance at the beginning of the period, liabilities								(45,828,000)	(1,909,000)
Included in Earnings, liabilities								13,367,000	(343,000)
Included in Other Comprehensive (Loss) Income, liabilities								3,025,000	(2,445,000)
Fair Value Of Contingent Consideration At Date Of Acquisition	8,800,000	41,400,000						8,813,000	41,387,000
Settlements, liabilities								8,109,000	256,000
Balance at the end of the period, liabilities								(30,140,000)	(45,828,000)
Auction rate securities
Cost Basis	159,418,000					10,000,000	10,000,000
Gross unrealized loss	1,387,000	4,784,000				3,900,000	1,100,000
Contingent consideration arrangment
Number of contingent consideration arrangements related to business acquisitions	5
Number of contingent consideration arrangements with payment limit	4
Business Acquisition Contingent Consideration Maximum Amount At Balance Sheet Date								166,900,000
Business Acquisition Contingent Consideration Fair Value at Balance Sheet Date With A Maximum Limit								29,500,000
Fair value of one contingent consideration arrangements without a maximum limit										700,000
Acquisition-related contingent consideration payments	8,109,000	256,000	10,781,000	7,400,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High				94,900,000	77,900,000
Fair Value, Discount Rate											15.00%
Contingent Consideration, Current				10,700,000
Contingent Consideration, Noncurrent				$ 19,600,000