GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - BALANCE SHEET (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
ASSETS
Cash and cash equivalents	$ 1,238,664	$ 1,481,447	$ 671,597	$ 990,405
Time deposits	87,500	0
Marketable securities	106,316	39,200
Accounts receivable, net	234,546	250,077
Other current assets	217,303	174,286
Property and equipment, net	304,963	302,817
Goodwill	2,198,558	2,245,364
Intangible assets, net	426,824	440,828
TOTAL ASSETS	5,052,343	5,188,691
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	65,000	40,000
Accounts payable, trade	96,503	86,883
Long-term debt, net of current portion	1,660,872	1,726,954
Income taxes payable	33,875	33,692
Redeemable noncontrolling interests	28,132	30,391
IAC shareholders' equity	2,065,438	1,804,526
Noncontrolling interests	61,073	411,299
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,052,343	5,188,691
Eliminations
ASSETS
Cash and cash equivalents	0	0
Time deposits	0
Marketable securities	0	0
Accounts receivable, net	0	0
Other current assets	0	0
Intercompany receivables	(1,757,994)	(1,600,470)
Property and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(4,231,487)	(3,585,828)
Other non-current assets	(10,092)	(14,991)
TOTAL ASSETS	(5,999,573)	(5,201,289)
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	(1,757,994)	(1,600,470)
Other long-term liabilities	(10,092)	(14,991)
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	(4,231,487)	(3,585,828)
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(5,999,573)	(5,201,289)
IAC
ASSETS
Cash and cash equivalents	804,901	1,073,053	464,884	762,231
Time deposits	0
Marketable securities	94,694	27,578
Accounts receivable, net	0	33
Other current assets	81,993	30,813
Intercompany receivables	0	0
Property and equipment, net	5,668	4,432
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	3,661,162	3,128,765
Other non-current assets	58,940	84,368
TOTAL ASSETS	4,707,358	4,349,042
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	25,000	0
Accounts payable, trade	2,658	4,711
Other current liabilities	38,360	62,833
Long-term debt, net of current portion	492,975	550,083
Income taxes payable	447	152
Intercompany liabilities	1,757,994	1,600,470
Other long-term liabilities	324,486	326,267
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	2,065,438	1,804,526
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,707,358	4,349,042
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	0	0	0	0
Time deposits	0
Marketable securities	0	0
Accounts receivable, net	112,952	117,337
Other current assets	49,534	48,884
Intercompany receivables	590,082	570,607
Property and equipment, net	199,202	201,242
Goodwill	776,571	830,642
Intangible assets, net	136,796	139,160
Investment in subsidiaries	570,325	457,063
Other non-current assets	10,797	13,428
TOTAL ASSETS	2,446,259	2,378,363
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0	0
Accounts payable, trade	53,242	43,240
Other current liabilities	167,389	182,848
Long-term debt, net of current portion	0	0
Income taxes payable	3,931	3,435
Intercompany liabilities	0	0
Other long-term liabilities	18,863	18,160
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	2,202,834	2,130,680
Noncontrolling interests	0	0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,446,259	2,378,363
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	433,763	408,394	206,713	228,174
Time deposits	87,500
Marketable securities	11,622	11,622
Accounts receivable, net	121,594	132,707
Other current assets	85,776	94,589
Intercompany receivables	1,167,912	1,029,863
Property and equipment, net	100,093	97,143
Goodwill	1,421,987	1,414,722
Intangible assets, net	290,028	301,668
Investment in subsidiaries	0	0
Other non-current assets	178,024	171,867
TOTAL ASSETS	3,898,299	3,662,575
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	40,000	40,000
Accounts payable, trade	40,603	38,932
Other current liabilities	409,690	395,982
Long-term debt, net of current portion	1,167,897	1,176,871
Income taxes payable	29,497	30,105
Intercompany liabilities	0	0
Other long-term liabilities	92,754	83,847
Redeemable noncontrolling interests	28,132	30,391
IAC shareholders' equity	2,028,653	1,455,148
Noncontrolling interests	61,073	411,299
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	3,898,299	3,662,575
IAC Consolidated
ASSETS
Cash and cash equivalents	1,238,664	1,481,447	$ 671,597	$ 990,405
Time deposits	87,500
Marketable securities	106,316	39,200
Accounts receivable, net	234,546	250,077
Other current assets	217,303	174,286
Intercompany receivables	0	0
Property and equipment, net	304,963	302,817
Goodwill	2,198,558	2,245,364
Intangible assets, net	426,824	440,828
Investment in subsidiaries	0	0
Other non-current assets	237,669	254,672
TOTAL ASSETS	5,052,343	5,188,691
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	65,000	40,000
Accounts payable, trade	96,503	86,883
Other current liabilities	615,439	641,663
Long-term debt, net of current portion	1,660,872	1,726,954
Income taxes payable	33,875	33,692
Intercompany liabilities	0	0
Other long-term liabilities	426,011	413,283
Redeemable noncontrolling interests	28,132	30,391
IAC shareholders' equity	2,065,438	1,804,526
Noncontrolling interests	61,073	411,299
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 5,052,343	$ 5,188,691