GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Dec. 21, 2012	Mar. 31, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 673,757	$ 749,977		$ 624,096	$ 704,153
Marketable securities	5,814	20,604
Accounts receivable, net	235,181	229,830
Other current assets	140,930	156,339
Property and equipment, net	293,282	270,512
Goodwill	1,674,220	1,616,154
Intangible assets, net	478,784	482,904
Other non-current assets	120,528	118,230
TOTAL ASSETS	3,780,246	3,805,828
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	78,168	98,314
Long-term debt, net of current maturities	580,000	580,000	580,000
Income taxes payable	481,908	479,945
Other long-term liabilities	66,405	31,830
Redeemable noncontrolling interests	59,254	58,126
IAC shareholders' equity	1,636,519	1,655,728
Noncontrolling interests	49,971	51,907
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,780,246	3,805,828
IAC
ASSETS
Cash and cash equivalents	430,356	501,075		447,293	545,222
Marketable securities	5,814
Accounts receivable, net	35
Other current assets	26,558
Intercompany receivables	0
Property and equipment, net	4,053
Goodwill	0
Intangible assets, net	0
Investment in subsidiaries	4,463,712
Other non-current assets	322,411
TOTAL ASSETS	5,252,939
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	3,983
Other Liabilities, Current	33,262
Long-term debt, net of current maturities	500,000
Income taxes payable	439,991
Intercompany liabilities	2,638,794
Other long-term liabilities	390
Redeemable noncontrolling interests	0
IAC shareholders' equity	1,636,519
Noncontrolling interests	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,252,939
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	0	0		0	0
Marketable securities	0
Accounts receivable, net	148,666
Other current assets	60,849
Intercompany receivables	536,367
Property and equipment, net	178,444
Goodwill	1,189,864
Intangible assets, net	331,408
Investment in subsidiaries	674,547
Other non-current assets	16,895
TOTAL ASSETS	3,137,040
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	42,672
Other Liabilities, Current	245,294
Long-term debt, net of current maturities	80,000
Income taxes payable	25,554
Intercompany liabilities	0
Other long-term liabilities	90,425
Redeemable noncontrolling interests	1,379
IAC shareholders' equity	2,651,716
Noncontrolling interests	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,137,040
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	243,401	248,902		176,803	158,931
Marketable securities	0
Accounts receivable, net	86,480
Other current assets	55,106
Intercompany receivables	1,790,850
Property and equipment, net	110,785
Goodwill	484,356
Intangible assets, net	147,376
Investment in subsidiaries	0
Other non-current assets	111,812
TOTAL ASSETS	3,030,166
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	31,513
Other Liabilities, Current	236,232
Long-term debt, net of current maturities	0
Income taxes payable	12,407
Intercompany liabilities	(311,577)
Other long-term liabilities	467,202
Redeemable noncontrolling interests	57,875
IAC shareholders' equity	2,486,543
Noncontrolling interests	49,971
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,030,166
Total Eliminations
ASSETS
Cash and cash equivalents	0	0		0	0
Marketable securities	0
Accounts receivable, net	0
Other current assets	(1,583)
Intercompany receivables	(2,327,217)
Property and equipment, net	0
Goodwill	0
Intangible assets, net	0
Investment in subsidiaries	(5,138,259)
Other non-current assets	(172,840)
TOTAL ASSETS	(7,639,899)
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	0
Other Liabilities, Current	(1,517)
Long-term debt, net of current maturities	0
Income taxes payable	3,956
Intercompany liabilities	(2,327,217)
Other long-term liabilities	(176,862)
Redeemable noncontrolling interests	0
IAC shareholders' equity	(5,138,259)
Noncontrolling interests	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(7,639,899)
IAC Consolidated
ASSETS
Cash and cash equivalents	673,757	749,977		624,096	704,153
Marketable securities	5,814
Accounts receivable, net	235,181
Other current assets	140,930
Intercompany receivables	0
Property and equipment, net	293,282
Goodwill	1,674,220
Intangible assets, net	478,784
Investment in subsidiaries	0
Other non-current assets	278,278
TOTAL ASSETS	3,780,246
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable, trade	78,168
Other Liabilities, Current	513,271
Long-term debt, net of current maturities	580,000
Income taxes payable	481,908
Intercompany liabilities	0
Other long-term liabilities	381,155
Redeemable noncontrolling interests	59,254
IAC shareholders' equity	1,636,519
Noncontrolling interests	49,971
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,780,246