GUARANTOR AND NONGUARANTOR FINANCIAL INFORMATION (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 990,405	$ 1,100,444	$ 749,977	$ 704,153
Marketable securities	160,648	6,004
Accounts receivable	236,086	207,408
Other current assets	166,742	161,530
Property and equipment, net	302,459	293,964
Goodwill	1,754,926	1,675,323	1,616,154
Intangible assets, net	491,936	445,336
Other non-current assets	56,693	164,685
TOTAL ASSETS	4,274,878	4,234,684
Accounts payable, trade	81,163	77,653
Long-term debt	1,080,000	1,080,000
Income taxes payable	32,635	416,384
Other long-term liabilities	45,191	58,393
Redeemable noncontrolling interests	40,427	42,861
Total IAC shareholders' equity	1,991,953	1,686,736
Noncontrolling interests	1,189	42,665
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,274,878	4,234,684
IAC
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	766,076	782,022	501,075	545,222
Marketable securities	159,197	1,007
Accounts receivable	13	38
Other current assets	23,923	45,111
Intercompany receivables	0	0
Property and equipment, net	4,950	5,316
Goodwill	0	0
Intangible assets, net	0	0
Equity Method Investments	5,035,304	3,833,751
Other non-current assets	44,610	83,207
TOTAL ASSETS	6,034,073	4,750,452
Accounts payable, trade	3,059	4,310
Other current liabilities	73,491	41,623
Long-term debt	1,000,000	1,000,000
Income taxes payable	2,240	383,926
Intercompany liabilities	2,659,213	1,416,453
Other long-term liabilities	304,117	217,404
Redeemable noncontrolling interests	0	0
Total IAC shareholders' equity	1,991,953	1,686,736
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	6,034,073	4,750,452
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	1,021	0	0	0
Marketable securities	0	0
Accounts receivable	155,262	135,651
Other current assets	91,105	76,572
Intercompany receivables	1,688,403	569,030
Property and equipment, net	232,819	221,386
Goodwill	1,249,807	1,180,159
Intangible assets, net	325,771	302,082
Equity Method Investments	930,443	782,840
Other non-current assets	20,682	15,521
TOTAL ASSETS	4,695,313	3,283,241
Accounts payable, trade	55,320	51,525
Other current liabilities	328,920	280,549
Long-term debt	80,000	80,000
Income taxes payable	4,771	6,768
Intercompany liabilities	0	0
Other long-term liabilities	104,219	96,239
Redeemable noncontrolling interests	0	0
Total IAC shareholders' equity	4,122,083	2,768,160
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,695,313	3,283,241
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	223,308	318,422	248,902	158,931
Marketable securities	1,451	4,997
Accounts receivable	80,811	71,719
Other current assets	57,487	40,661
Intercompany receivables	970,810	847,423
Property and equipment, net	64,690	67,262
Goodwill	505,119	495,164
Intangible assets, net	166,165	143,254
Equity Method Investments	0	0
Other non-current assets	109,372	252,576
TOTAL ASSETS	2,179,213	2,241,478
Accounts payable, trade	22,784	21,818
Other current liabilities	191,197	187,072
Long-term debt	0	0
Income taxes payable	25,624	25,690
Intercompany liabilities	0	0
Other long-term liabilities	54,328	72,941
Redeemable noncontrolling interests	40,427	42,861
Total IAC shareholders' equity	1,843,664	1,848,431
Noncontrolling interests	1,189	42,665
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,179,213	2,241,478
IAC Consolidated
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	990,405	1,100,444	749,977	704,153
Marketable securities	160,648	6,004
Accounts receivable	236,086	207,408
Other current assets	166,742	161,530
Intercompany receivables	0	0
Property and equipment, net	302,459	293,964
Goodwill	1,754,926	1,675,323
Intangible assets, net	491,936	445,336
Equity Method Investments	0	0
Other non-current assets	171,676	344,675
TOTAL ASSETS	4,274,878	4,234,684
Accounts payable, trade	81,163	77,653
Other current liabilities	592,791	509,244
Long-term debt	1,080,000	1,080,000
Income taxes payable	32,635	416,384
Intercompany liabilities	0	0
Other long-term liabilities	454,720	379,141
Redeemable noncontrolling interests	40,427	42,861
Total IAC shareholders' equity	1,991,953	1,686,736
Noncontrolling interests	1,189	42,665
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,274,878	4,234,684
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0
Marketable securities	0	0
Accounts receivable	0	0
Other current assets	(5,773)	(814)
Intercompany receivables	(2,659,213)	(1,416,453)
Property and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Equity Method Investments	(5,965,747)	(4,616,591)
Other non-current assets	(2,988)	(6,629)
TOTAL ASSETS	(8,633,721)	(6,040,487)
Accounts payable, trade	0	0
Other current liabilities	(817)	0
Long-term debt	0	0
Income taxes payable	0	0
Intercompany liabilities	(2,659,213)	(1,416,453)
Other long-term liabilities	(7,944)	(7,443)
Redeemable noncontrolling interests	0	0
Total IAC shareholders' equity	(5,965,747)	(4,616,591)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ (8,633,721)	$ (6,040,487)