GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 741,652	$ 749,977	$ 501,779	$ 704,153
Marketable securities	26,340	20,604
Accounts receivable, net	209,949	229,830
Other current assets	151,980	156,339
Property and equipment, net	290,470	270,512
Goodwill	1,672,705	1,616,154
Intangible assets, net	458,371	482,904
Other non-current assets	89,145	118,230
TOTAL ASSETS	3,804,782	3,805,828
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	72,966	98,314
Long-term debt, net of current maturities	580,000	580,000
Income taxes payable	411,172	479,945
Other long-term liabilities	65,175	31,830
Redeemable noncontrolling interests	32,779	58,126
IAC shareholders' equity	1,735,056	1,655,728
Noncontrolling interests	52,940	51,907
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,804,782	3,805,828
IAC
ASSETS
Cash and cash equivalents	452,097	501,075	268,199	545,222
Marketable securities	15,445	20,604
Accounts receivable, net	19	43
Other current assets	43,317	58,452
Intercompany receivables	0	0
Property and equipment, net	4,088	4,116
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	4,510,043	12,913,694
Other non-current assets	87,167	153,155
TOTAL ASSETS	5,112,176	13,651,139
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	2,262	4,366
Other Liabilities, Current	69,965	74,214
Long-term debt, net of current maturities	500,000	500,000
Income taxes payable	358,327	440,110
Intercompany liabilities	2,221,147	10,759,104
Other long-term liabilities	225,419	217,617
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	1,735,056	1,655,728
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,112,176	13,651,139
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	129,189	142,627
Other current assets	68,415	53,720
Intercompany receivables	498,273	482,926
Property and equipment, net	217,650	194,515
Goodwill	1,179,888	1,190,199
Intangible assets, net	310,248	340,631
Investment in subsidiaries	697,685	611,851
Other non-current assets	20,647	16,509
TOTAL ASSETS	3,121,995	3,032,978
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	39,414	64,888
Other Liabilities, Current	252,040	216,010
Long-term debt, net of current maturities	80,000	80,000
Income taxes payable	25,199	26,389
Intercompany liabilities	0	0
Other long-term liabilities	85,975	91,119
Redeemable noncontrolling interests	0	1,388
IAC shareholders' equity	2,639,367	2,553,184
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,121,995	3,032,978
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	289,555	248,902	233,580	158,931
Marketable securities	10,895	0
Accounts receivable, net	80,741	87,160
Other current assets	41,229	45,204
Intercompany receivables	1,722,874	10,276,178
Property and equipment, net	68,732	71,881
Goodwill	492,817	425,955
Intangible assets, net	148,123	142,273
Investment in subsidiaries	0	0
Other non-current assets	150,354	109,912
TOTAL ASSETS	3,005,320	11,407,465
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	31,290	29,060
Other Liabilities, Current	208,295	238,003
Long-term debt, net of current maturities	0	0
Income taxes payable	27,646	13,446
Intercompany liabilities	0	0
Other long-term liabilities	84,009	45,950
Redeemable noncontrolling interests	32,779	56,738
IAC shareholders' equity	2,568,361	10,972,361
Noncontrolling interests	52,940	51,907
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,005,320	11,407,465
Total Eliminations
ASSETS
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	0	0
Other current assets	(981)	(1,037)
Intercompany receivables	(2,221,147)	(10,759,104)
Property and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(5,207,728)	(13,525,545)
Other non-current assets	(4,853)	(68)
TOTAL ASSETS	(7,434,709)	(24,285,754)
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	0	0
Other Liabilities, Current	(1,715)	(1,652)
Long-term debt, net of current maturities	0	0
Income taxes payable	0	0
Intercompany liabilities	(2,221,147)	(10,759,104)
Other long-term liabilities	(4,119)	547
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	(5,207,728)	(13,525,545)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(7,434,709)	(24,285,754)
IAC Consolidated
ASSETS
Cash and cash equivalents	741,652	749,977	501,779	704,153
Marketable securities	26,340	20,604
Accounts receivable, net	209,949	229,830
Other current assets	151,980	156,339
Intercompany receivables	0	0
Property and equipment, net	290,470	270,512
Goodwill	1,672,705	1,616,154
Intangible assets, net	458,371	482,904
Investment in subsidiaries	0	0
Other non-current assets	253,315	279,508
TOTAL ASSETS	3,804,782	3,805,828
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	72,966	98,314
Other Liabilities, Current	528,585	526,575
Long-term debt, net of current maturities	580,000	580,000
Income taxes payable	411,172	479,945
Intercompany liabilities	0	0
Other long-term liabilities	391,284	355,233
Redeemable noncontrolling interests	32,779	58,126
IAC shareholders' equity	1,735,056	1,655,728
Noncontrolling interests	52,940	51,907
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,804,782	$ 3,805,828