GUARANTOR AND NONGUARANTOR FINANCIAL INFORMATION - CONDENSED BALANCE SHEET (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Balance Sheet
Cash and cash equivalents	$ 1,481,447	$ 990,405	$ 1,100,444	$ 749,977
Marketable securities	39,200	160,648
Accounts receivable, net	250,077	236,086
Other current assets	174,286	148,749
Intercompany receivables	0	0
Property and equipment, net	302,817	302,459
Goodwill	2,245,364	1,754,926
Intangible assets, net	440,828	491,936
Investment in subsidiaries	0	0
Other non-current assets	275,931	171,676
TOTAL ASSETS	5,209,950	4,256,885
Current portion of long-term debt	40,000	0
Accounts payable, trade	86,883	81,163
Other current liabilities	641,663	592,537
Long-term debt, net of current maturities	1,748,213	1,080,000
Income taxes payable	33,692	32,635
Intercompany liabilities	0	0
Other long-term liabilities	413,283	436,981
Redeemable noncontrolling interests	30,391	40,427
Total IAC shareholders' equity	1,804,526	1,991,953
Noncontrolling interests	411,299	1,189
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,209,950	4,256,885
Inter-segment Elimination
Condensed Balance Sheet
Cash and cash equivalents	0	0
Marketable securities	0	0
Accounts receivable, net	0	0
Other current assets	0	0
Intercompany receivables	(1,600,470)	(2,655,368)
Property and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(3,587,273)	(5,501,469)
Other non-current assets	(14,991)	0
TOTAL ASSETS	(5,202,734)	(8,156,837)
Current portion of long-term debt	0
Accounts payable, trade	0	0
Other current liabilities	0	0
Long-term debt, net of current maturities	0	0
Income taxes payable	0	0
Intercompany liabilities	(1,600,470)	(2,655,368)
Other long-term liabilities	(14,991)	0
Redeemable noncontrolling interests	0	0
Total IAC shareholders' equity	(3,587,273)	(5,501,469)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(5,202,734)	(8,156,837)
IAC
Condensed Balance Sheet
Cash and cash equivalents	1,073,053	762,231	780,651	499,332
Marketable securities	27,578	159,197
Accounts receivable, net	33	13
Other current assets	30,813	20,532
Intercompany receivables	0	0
Property and equipment, net	4,432	4,950
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	3,128,765	5,035,304
Other non-current assets	89,017	44,610
TOTAL ASSETS	4,353,691	6,026,837
Current portion of long-term debt	0
Accounts payable, trade	4,711	3,059
Other current liabilities	62,833	73,491
Long-term debt, net of current maturities	554,732	1,000,000
Income taxes payable	152	2,240
Intercompany liabilities	1,600,470	2,655,368
Other long-term liabilities	326,267	300,726
Redeemable noncontrolling interests	0	0
Total IAC shareholders' equity	1,804,526	1,991,953
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,353,691	6,026,837
Guarantor Subsidiaries
Condensed Balance Sheet
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	117,337	137,593
Other current assets	48,884	55,422
Intercompany receivables	570,607	691,357
Property and equipment, net	201,242	207,407
Goodwill	830,642	840,104
Intangible assets, net	139,160	243,408
Investment in subsidiaries	457,063	466,165
Other non-current assets	13,428	13,228
TOTAL ASSETS	2,378,363	2,654,684
Current portion of long-term debt	0
Accounts payable, trade	43,240	50,761
Other current liabilities	182,848	187,698
Long-term debt, net of current maturities	0	80,000
Income taxes payable	3,435	2,929
Intercompany liabilities	0	0
Other long-term liabilities	18,160	59,889
Redeemable noncontrolling interests	0	0
Total IAC shareholders' equity	2,130,680	2,273,407
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,378,363	2,654,684
Non-Guarantor Subsidiaries
Condensed Balance Sheet
Cash and cash equivalents	408,394	228,174	$ 319,793	$ 250,645
Marketable securities	11,622	1,451
Accounts receivable, net	132,707	98,480
Other current assets	94,589	72,795
Intercompany receivables	1,029,863	1,964,011
Property and equipment, net	97,143	90,102
Goodwill	1,414,722	914,822
Intangible assets, net	301,668	248,528
Investment in subsidiaries	1,445	0
Other non-current assets	188,477	113,838
TOTAL ASSETS	3,680,630	3,732,201
Current portion of long-term debt	40,000
Accounts payable, trade	38,932	27,343
Other current liabilities	395,982	331,348
Long-term debt, net of current maturities	1,193,481	0
Income taxes payable	30,105	27,466
Intercompany liabilities	0	0
Other long-term liabilities	83,847	76,366
Redeemable noncontrolling interests	30,391	40,427
Total IAC shareholders' equity	1,456,593	3,228,062
Noncontrolling interests	411,299	1,189
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,680,630	$ 3,732,201