GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - BALANCE SHEET (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
ASSETS
Cash and cash equivalents	$ 1,245,984	$ 1,481,447	$ 656,409	$ 990,405
Marketable securities	79,208	39,200
Accounts receivable, net	189,491	250,077
Other current assets	278,185	174,286
Intercompany receivables	0	0
Property and equipment, net	306,999	302,817
Goodwill	1,937,675	2,245,364
Intangible assets, net	395,262	440,828
Investment in subsidiaries	0	0
Other non-current assets	227,218	254,672
TOTAL ASSETS	4,660,022	5,188,691
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	50,000	40,000
Accounts payable, trade	61,749	86,883
Other current liabilities	580,457	641,663
Long-term debt, net of current portion	1,655,259	1,726,954
Income taxes payable	33,083	33,692
Intercompany liabilities	0	0
Other long-term liabilities	342,120	413,283
Redeemable noncontrolling interests	38,421	30,391
IAC shareholders' equity	1,814,450	1,804,526
Noncontrolling interests	84,483	411,299
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,660,022	5,188,691
Eliminations
ASSETS
Cash and cash equivalents	0	0
Marketable securities	0	0
Accounts receivable, net	0	0
Other current assets	0	0
Intercompany receivables	(1,792,198)	(1,600,470)
Property and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(4,118,494)	(3,595,366)
Other non-current assets	(109,036)	(14,992)
TOTAL ASSETS	(6,019,728)	(5,210,828)
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0	0
Accounts payable, trade	0	0
Other current liabilities	0	0
Long-term debt, net of current portion	0	0
Income taxes payable	0	0
Intercompany liabilities	(1,792,198)	(1,600,470)
Other long-term liabilities	(109,036)	(14,992)
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	(4,118,494)	(3,595,366)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(6,019,728)	(5,210,828)
IAC
ASSETS
Cash and cash equivalents	680,859	1,073,053	428,314	762,231
Marketable securities	79,208	27,578
Accounts receivable, net	0	33
Other current assets	124,877	30,813
Intercompany receivables	0	0
Property and equipment, net	5,190	4,432
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	3,520,513	3,128,765
Other non-current assets	51,803	84,368
TOTAL ASSETS	4,462,450	4,349,042
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	50,000	0
Accounts payable, trade	3,089	4,711
Other current liabilities	28,622	62,833
Long-term debt, net of current portion	440,471	550,083
Income taxes payable	445	152
Intercompany liabilities	1,792,198	1,600,470
Other long-term liabilities	333,175	326,267
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	1,814,450	1,804,526
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,462,450	4,349,042
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	0	0	0	0
Marketable securities	0	0
Accounts receivable, net	88,726	115,280
Other current assets	44,075	46,128
Intercompany receivables	634,253	637,324
Property and equipment, net	193,923	198,890
Goodwill	529,403	776,569
Intangible assets, net	106,734	135,817
Investment in subsidiaries	597,981	466,601
Other non-current assets	104,751	11,258
TOTAL ASSETS	2,299,846	2,387,867
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0	0
Accounts payable, trade	37,191	42,104
Other current liabilities	105,392	140,077
Long-term debt, net of current portion	0	0
Income taxes payable	3,937	3,435
Intercompany liabilities	0	0
Other long-term liabilities	18,671	18,160
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	2,134,655	2,184,091
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,299,846	2,387,867
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	565,125	408,394	$ 228,095	$ 228,174
Marketable securities	0	11,622
Accounts receivable, net	100,765	134,764
Other current assets	109,233	97,345
Intercompany receivables	1,157,945	963,146
Property and equipment, net	107,886	99,495
Goodwill	1,408,272	1,468,795
Intangible assets, net	288,528	305,011
Investment in subsidiaries	0	0
Other non-current assets	179,700	174,038
TOTAL ASSETS	3,917,454	3,662,610
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0	40,000
Accounts payable, trade	21,469	40,068
Other current liabilities	446,443	438,753
Long-term debt, net of current portion	1,214,788	1,176,871
Income taxes payable	28,701	30,105
Intercompany liabilities	0	0
Other long-term liabilities	99,310	83,848
Redeemable noncontrolling interests	38,421	30,391
IAC shareholders' equity	1,983,839	1,411,275
Noncontrolling interests	84,483	411,299
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,917,454	$ 3,662,610