SEGMENT INFORMATION (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment reporting information
Revenue	$ 724,455,000	$ 756,872,000	$ 799,411,000	$ 742,249,000	$ 765,251,000	$ 714,470,000	$ 680,612,000	$ 640,600,000	$ 3,022,987,000	$ 2,800,933,000	$ 2,059,444,000
Operating Income Before Amortization									539,394,000	444,964,000	308,407,000
Segment Assets	2,114,025,000				1,706,770,000				2,114,025,000	1,706,770,000
Depreciation									58,909,000	52,481,000	56,719,000
Capital expenditures									80,311,000	51,201,000	39,954,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									539,394,000	444,964,000	308,407,000
Non-Cash Compensation Expense									(53,005,000)	(85,625,000)	(88,588,000)
Amortization of Intangibles									(59,843,000)	(35,771,000)	(22,057,000)
Acquisition-related contingent consideration fair value adjustments									(343,000)	0	0
Operating income	112,952,000	122,004,000	106,696,000	84,551,000	85,294,000	78,033,000	97,476,000	62,765,000	426,203,000	323,568,000	197,762,000
Reconciliation of segment assets to total assets
Segment Assets	2,114,025,000				1,706,770,000				2,114,025,000	1,706,770,000
Goodwill	1,675,323,000				1,616,154,000				1,675,323,000	1,616,154,000	1,358,524,000
Indefinite-Lived Intangible Assets	376,329,000				378,964,000				376,329,000	378,964,000
Definite-Lived Intangible Assets	69,007,000				103,940,000				69,007,000	103,940,000
TOTAL ASSETS	4,234,684,000				3,805,828,000				4,234,684,000	3,805,828,000
Search & Applications
Segment reporting information
Revenue									1,604,950,000	1,465,795,000	1,040,507,000
Operating Income Before Amortization									367,674,000	313,146,000	204,980,000
Segment Assets	409,116,000				355,159,000				409,116,000	355,159,000
Depreciation									18,177,000	14,995,000	25,484,000
Capital expenditures									22,215,000	15,320,000	8,698,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									367,674,000	313,146,000	204,980,000
Non-Cash Compensation Expense									(3,000)	(34,000)	202,000
Amortization of Intangibles									(27,554,000)	(7,468,000)	(1,176,000)
Operating income									340,117,000	305,644,000	204,006,000
Reconciliation of segment assets to total assets
Segment Assets	409,116,000				355,159,000				409,116,000	355,159,000
Goodwill	738,062,000				723,650,000				738,062,000	723,650,000	526,444,000
Indefinite-Lived Intangible Assets	195,805,000				197,304,000				195,805,000	197,304,000
Definite-Lived Intangible Assets	40,550,000				64,457,000				40,550,000	64,457,000
TOTAL ASSETS	1,383,533,000				1,340,570,000				1,383,533,000	1,340,570,000
Match
Segment reporting information
Revenue									788,197,000	713,449,000	518,027,000
Operating Income Before Amortization									262,159,000	225,765,000	156,274,000
Segment Assets	325,939,000				225,781,000				325,939,000	225,781,000
Depreciation									19,991,000	16,339,000	10,780,000
Capital expenditures									19,587,000	19,853,000	17,447,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									262,159,000	225,765,000	156,274,000
Non-Cash Compensation Expense									(1,122,000)	(2,818,000)	(1,642,000)
Amortization of Intangibles									(15,138,000)	(17,455,000)	(17,077,000)
Acquisition-related contingent consideration fair value adjustments									(343,000)
Operating income									245,556,000	205,492,000	137,555,000
Reconciliation of segment assets to total assets
Segment Assets	325,939,000				225,781,000				325,939,000	225,781,000
Goodwill	751,232,000				683,935,000				751,232,000	683,935,000	667,073,000
Indefinite-Lived Intangible Assets	162,344,000				158,098,000				162,344,000	158,098,000
Definite-Lived Intangible Assets	5,405,000				5,612,000				5,405,000	5,612,000
TOTAL ASSETS	1,244,920,000				1,073,426,000				1,244,920,000	1,073,426,000
Local
Segment reporting information
Revenue									277,466,000	322,627,000	303,418,000
Operating Income Before Amortization									13,023,000	24,932,000	28,284,000
Segment Assets	25,522,000				46,842,000				25,522,000	46,842,000
Depreciation									7,657,000	10,136,000	10,388,000
Capital expenditures									7,016,000	6,666,000	9,299,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									13,023,000	24,932,000	28,284,000
Non-Cash Compensation Expense
Amortization of Intangibles									(13,415,000)	(3,197,000)	(2,751,000)
Operating income									(392,000)	21,735,000	25,533,000
Reconciliation of segment assets to total assets
Segment Assets	25,522,000				46,842,000				25,522,000	46,842,000
Goodwill	131,872,000				143,782,000				131,872,000	143,782,000	127,698,000
Indefinite-Lived Intangible Assets					5,382,000					5,382,000
Definite-Lived Intangible Assets	14,027,000				21,104,000				14,027,000	21,104,000
TOTAL ASSETS	171,421,000				217,110,000				171,421,000	217,110,000
Media
Segment reporting information
Revenue									193,734,000	164,824,000	70,164,000
Operating Income Before Amortization									(28,157,000)	(44,827,000)	(15,845,000)
Segment Assets	93,074,000				71,495,000				93,074,000	71,495,000
Depreciation									2,124,000	1,398,000	703,000
Capital expenditures									1,386,000	1,178,000	905,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									(28,157,000)	(44,827,000)	(15,845,000)
Non-Cash Compensation Expense									(633,000)	(770,000)	(427,000)
Amortization of Intangibles									(1,070,000)	(6,179,000)	(3,000)
Operating income									(29,860,000)	(51,776,000)	(16,275,000)
Reconciliation of segment assets to total assets
Segment Assets	93,074,000				71,495,000				93,074,000	71,495,000
Goodwill	15,590,000				15,590,000				15,590,000	15,590,000	15,590,000
Indefinite-Lived Intangible Assets	1,800,000				1,800,000				1,800,000	1,800,000
Definite-Lived Intangible Assets	944,000				2,020,000				944,000	2,020,000
TOTAL ASSETS	111,408,000				90,905,000				111,408,000	90,905,000
Other Segment
Segment reporting information
Revenue									159,493,000	134,555,000	128,065,000
Operating Income Before Amortization									(6,138,000)	(6,095,000)	(2,499,000)
Segment Assets	45,340,000				28,842,000				45,340,000	28,842,000
Depreciation									1,442,000	1,074,000	851,000
Capital expenditures									2,126,000	1,819,000	970,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									(6,138,000)	(6,095,000)	(2,499,000)
Non-Cash Compensation Expense									(33,000)	(122,000)	(347,000)
Amortization of Intangibles									(2,666,000)	(1,472,000)	(1,050,000)
Operating income									(8,837,000)	(7,689,000)	(3,896,000)
Reconciliation of segment assets to total assets
Segment Assets	45,340,000				28,842,000				45,340,000	28,842,000
Goodwill	38,567,000				49,197,000				38,567,000	49,197,000
Indefinite-Lived Intangible Assets	16,380,000				16,380,000				16,380,000	16,380,000
Definite-Lived Intangible Assets	8,081,000				10,747,000				8,081,000	10,747,000
TOTAL ASSETS	108,368,000				105,166,000				108,368,000	105,166,000
Total Eliminations
Segment reporting information
Revenue									(853,000)	(317,000)	(737,000)
Corporate
Segment reporting information
Operating Income Before Amortization									(69,167,000)	(67,957,000)	(62,787,000)
Segment Assets	1,215,034,000				978,651,000				1,215,034,000	978,651,000
Depreciation									9,518,000	8,539,000	8,513,000
Capital expenditures									27,981,000	6,365,000	2,635,000
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments
Operating Income Before Amortization									(69,167,000)	(67,957,000)	(62,787,000)
Non-Cash Compensation Expense									(51,214,000)	(81,881,000)	(86,374,000)
Amortization of Intangibles
Operating income									(120,381,000)	(149,838,000)	(149,161,000)
Reconciliation of segment assets to total assets
Segment Assets	1,215,034,000				978,651,000				1,215,034,000	978,651,000
Goodwill
Indefinite-Lived Intangible Assets
Definite-Lived Intangible Assets
TOTAL ASSETS	$ 1,215,034,000				$ 978,651,000				$ 1,215,034,000	$ 978,651,000