GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 1,003,311	$ 1,100,444	$ 673,757	$ 749,977
Marketable securities	39,543	6,004
Accounts receivable, net	241,017	207,408
Other current assets	187,205	161,530
Property and equipment, net of accumulated depreciation and amortization of $277,498 and $265,298, respectively	291,111	293,964
Goodwill	1,715,601	1,675,323
Intangible assets, net of accumulated amortization of $93,366 and $83,310, respectively	472,237	445,336
Other non-current assets	89,749	164,685
TOTAL ASSETS	4,224,056	4,234,684
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	67,516	77,653
Long-term debt	1,080,000	1,080,000
Income taxes payable	420,256	416,384
Other long-term liabilities	61,706	58,393
Redeemable noncontrolling interests	25,885	42,861
IAC shareholders' equity	1,709,494	1,686,736
Noncontrolling interests	1,730	42,665
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,224,056	4,234,684
IAC
ASSETS
Cash and cash equivalents	670,607	782,022	430,356	501,075
Marketable securities	33,961	1,007
Accounts receivable, net	30	38
Other current assets	63,187	45,111
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization of $277,498 and $265,298, respectively	5,108	5,316
Goodwill	0	0
Intangible assets, net of accumulated amortization of $93,366 and $83,310, respectively	0	0
Investment in subsidiaries	3,857,408	3,833,751
Other non-current assets	85,073	83,207
TOTAL ASSETS	4,715,374	4,750,452
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	5,023	4,310
Other Liabilities, Current	40,684	41,623
Long-term debt	1,000,000	1,000,000
Income taxes payable	386,168	383,926
Intercompany liabilities	1,354,867	1,416,453
Other long-term liabilities	219,138	217,404
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	1,709,494	1,686,736
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,715,374	4,750,452
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	148,753	134,307
Other current assets	75,085	73,487
Intercompany receivables	524,844	564,999
Property and equipment, net of accumulated depreciation and amortization of $277,498 and $265,298, respectively	218,643	220,756
Goodwill	1,185,760	1,180,159
Intangible assets, net of accumulated amortization of $93,366 and $83,310, respectively	293,311	301,513
Investment in subsidiaries	825,826	782,840
Other non-current assets	19,132	15,485
TOTAL ASSETS	3,291,354	3,273,546
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	33,202	51,302
Other Liabilities, Current	269,022	254,882
Long-term debt	80,000	80,000
Income taxes payable	7,785	6,768
Intercompany liabilities	0	0
Other long-term liabilities	94,941	96,091
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	2,806,404	2,784,503
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,291,354	3,273,546
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	332,704	318,422	243,401	248,902
Marketable securities	5,582	4,997
Accounts receivable, net	92,234	73,063
Other current assets	49,977	43,746
Intercompany receivables	830,023	851,454
Property and equipment, net of accumulated depreciation and amortization of $277,498 and $265,298, respectively	67,360	67,892
Goodwill	529,841	495,164
Intangible assets, net of accumulated amortization of $93,366 and $83,310, respectively	178,926	143,823
Investment in subsidiaries	0	0
Other non-current assets	175,914	252,612
TOTAL ASSETS	2,262,561	2,251,173
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	29,291	22,041
Other Liabilities, Current	223,421	212,739
Long-term debt	0	0
Income taxes payable	26,303	25,690
Intercompany liabilities	0	0
Other long-term liabilities	79,101	73,089
Redeemable noncontrolling interests	25,885	42,861
IAC shareholders' equity	1,876,830	1,832,088
Noncontrolling interests	1,730	42,665
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,262,561	2,251,173
Total Eliminations
ASSETS
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	0	0
Other current assets	(1,044)	(814)
Intercompany receivables	(1,354,867)	(1,416,453)
Property and equipment, net of accumulated depreciation and amortization of $277,498 and $265,298, respectively	0	0
Goodwill	0	0
Intangible assets, net of accumulated amortization of $93,366 and $83,310, respectively	0	0
Investment in subsidiaries	(4,683,234)	(4,616,591)
Other non-current assets	(6,088)	(6,629)
TOTAL ASSETS	(6,045,233)	(6,040,487)
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	0	0
Other Liabilities, Current	0	0
Long-term debt	0	0
Income taxes payable	0	0
Intercompany liabilities	(1,354,867)	(1,416,453)
Other long-term liabilities	(7,132)	(7,443)
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	(4,683,234)	(4,616,591)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(6,045,233)	(6,040,487)
IAC Consolidated
ASSETS
Cash and cash equivalents	1,003,311	1,100,444	673,757	749,977
Marketable securities	39,543	6,004
Accounts receivable, net	241,017	207,408
Other current assets	187,205	161,530
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization of $277,498 and $265,298, respectively	291,111	293,964
Goodwill	1,715,601	1,675,323
Intangible assets, net of accumulated amortization of $93,366 and $83,310, respectively	472,237	445,336
Investment in subsidiaries	0	0
Other non-current assets	274,031	344,675
TOTAL ASSETS	4,224,056	4,234,684
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	67,516	77,653
Other Liabilities, Current	533,127	509,244
Long-term debt	1,080,000	1,080,000
Income taxes payable	420,256	416,384
Intercompany liabilities	0	0
Other long-term liabilities	386,048	379,141
Redeemable noncontrolling interests	25,885	42,861
IAC shareholders' equity	1,709,494	1,686,736
Noncontrolling interests	1,730	42,665
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 4,224,056	$ 4,234,684