GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
ASSETS
Cash and cash equivalents	$ 656,409	$ 990,405	$ 987,326	$ 1,100,444
Marketable securities	233,523	160,648
Accounts receivable, net	223,106	236,086
Other current assets	209,724	166,742
Property and equipment, net of accumulated depreciation and amortization of $294,400 and $279,534, respectively	297,158	302,459
Goodwill	1,778,830	1,754,926
Intangible assets, net	472,082	491,936
Other non-current assets	72,841	56,693
TOTAL ASSETS	4,075,058	4,274,878
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	80,000	0
Accounts payable, trade	79,434	81,163
Long-term debt, net of current portion	1,000,000	1,080,000
Income taxes payable	24,768	32,635
Other long-term liabilities	59,182	45,191
Redeemable noncontrolling interests	28,177	40,427
IAC shareholders' equity	1,815,386	1,991,953
Noncontrolling interests	0	1,189
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,075,058	4,274,878
Intersegment eliminations
ASSETS
Cash and cash equivalents	0	0
Marketable securities	0	0
Accounts receivable, net	0	0
Other current assets	(4,871)	(5,773)
Intercompany receivables	(2,577,772)	(2,659,213)
Property and equipment, net of accumulated depreciation and amortization of $294,400 and $279,534, respectively	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(5,903,532)	(5,965,747)
Other non-current assets	(1,538)	(2,988)
TOTAL ASSETS	(8,487,713)	(8,633,721)
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0
Accounts payable, trade	0	0
Other current liabilities	(738)	(817)
Long-term debt, net of current portion	0	0
Income taxes payable	0	0
Intercompany liabilities	(2,577,772)	(2,659,213)
Other long-term liabilities	(5,671)	(7,944)
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	(5,903,532)	(5,965,747)
Noncontrolling interests		0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	(8,487,713)	(8,633,721)
IAC Consolidated
ASSETS
Cash and cash equivalents	656,409	990,405	987,326	1,100,444
Marketable securities	233,523	160,648
Accounts receivable, net	223,106	236,086
Other current assets	209,724	166,742
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization of $294,400 and $279,534, respectively	297,158	302,459
Goodwill	1,778,830	1,754,926
Intangible assets, net	472,082	491,936
Investment in subsidiaries	0	0
Other non-current assets	204,226	171,676
TOTAL ASSETS	4,075,058	4,274,878
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	80,000
Accounts payable, trade	79,434	81,163
Other current liabilities	555,423	592,791
Long-term debt, net of current portion	1,000,000	1,080,000
Income taxes payable	24,768	32,635
Intercompany liabilities	0	0
Other long-term liabilities	491,870	454,720
Redeemable noncontrolling interests	28,177	40,427
IAC shareholders' equity	1,815,386	1,991,953
Noncontrolling interests		1,189
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,075,058	4,274,878
IAC
ASSETS
Cash and cash equivalents	431,731	766,076	732,792	782,022
Marketable securities	232,917	159,197
Accounts receivable, net	4	13
Other current assets	47,233	23,923
Intercompany receivables	0	0
Property and equipment, net of accumulated depreciation and amortization of $294,400 and $279,534, respectively	4,867	4,950
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	4,971,322	5,035,304
Other non-current assets	69,644	44,610
TOTAL ASSETS	5,757,718	6,034,073
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0
Accounts payable, trade	3,078	3,059
Other current liabilities	32,661	73,491
Long-term debt, net of current portion	1,000,000	1,000,000
Income taxes payable	892	2,240
Intercompany liabilities	2,577,772	2,659,213
Other long-term liabilities	327,929	304,117
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	1,815,386	1,991,953
Noncontrolling interests		0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	5,757,718	6,034,073
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	4,121	1,021	0	0
Marketable securities	0	0
Accounts receivable, net	132,223	155,262
Other current assets	97,670	91,105
Intercompany receivables	1,635,189	1,688,403
Property and equipment, net of accumulated depreciation and amortization of $294,400 and $279,534, respectively	228,061	232,819
Goodwill	1,250,801	1,249,807
Intangible assets, net	313,275	325,771
Investment in subsidiaries	932,210	930,443
Other non-current assets	20,715	20,682
TOTAL ASSETS	4,614,265	4,695,313
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	80,000
Accounts payable, trade	57,265	55,320
Other current liabilities	320,261	328,920
Long-term debt, net of current portion	0	80,000
Income taxes payable	4,829	4,771
Intercompany liabilities	0	0
Other long-term liabilities	100,370	104,219
Redeemable noncontrolling interests	0	0
IAC shareholders' equity	4,051,540	4,122,083
Noncontrolling interests		0
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,614,265	4,695,313
Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	220,557	223,308	$ 254,534	$ 318,422
Marketable securities	606	1,451
Accounts receivable, net	90,879	80,811
Other current assets	69,692	57,487
Intercompany receivables	942,583	970,810
Property and equipment, net of accumulated depreciation and amortization of $294,400 and $279,534, respectively	64,230	64,690
Goodwill	528,029	505,119
Intangible assets, net	158,807	166,165
Investment in subsidiaries	0	0
Other non-current assets	115,405	109,372
TOTAL ASSETS	2,190,788	2,179,213
LIABILITIES AND SHAREHOLDERS' EQUITY
Current portion of long-term debt	0
Accounts payable, trade	19,091	22,784
Other current liabilities	203,239	191,197
Long-term debt, net of current portion	0	0
Income taxes payable	19,047	25,624
Intercompany liabilities	0	0
Other long-term liabilities	69,242	54,328
Redeemable noncontrolling interests	28,177	40,427
IAC shareholders' equity	1,851,992	1,843,664
Noncontrolling interests		1,189
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 2,190,788	$ 2,179,213