CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 3,307,239	$ 3,139,882	$ 3,230,933
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	651,008	755,730	778,161
Selling and marketing expense	1,381,221	1,247,097	1,348,293
General and administrative expense	719,257	530,446	512,055
Product development expense	250,879	212,765	196,623
Depreciation	74,265	71,676	62,205
Amortization of intangibles	42,143	79,426	139,952
Goodwill impairment	0	275,367	14,056
Total operating costs and expenses	3,118,773	3,172,507	3,051,345
Operating income (loss)	188,466	(32,625)	179,588
Interest expense	(105,295)	(109,110)	(73,636)
Other (expense) income, net	(16,213)	60,650	36,938
Earnings (loss) before income taxes	66,958	(81,085)	142,890
Income tax benefit (provision)	291,050	64,934	(29,516)
Net earnings (loss)	358,008	(16,151)	113,374
Net (earnings) loss attributable to noncontrolling interests	(53,084)	(25,129)	6,098
Net earnings (loss) attributable to IAC shareholders	$ 304,924	$ (41,280)	$ 119,472
Per share information attributable to IAC shareholders:
Basic earnings (loss) per share (USD per share)	$ 3.81	$ (0.52)	$ 1.44
Diluted earnings (loss) per share (USD per share)	3.18	(0.52)	1.33
Dividends declared per share (in usd per share)	$ 0	$ 0	$ 1.36
Stock-based compensation expense by function:
Stock-based compensation expense	$ 264,618	$ 104,820	$ 105,450
Cost of revenue
Stock-based compensation expense by function:
Stock-based compensation expense	1,881	2,305	1,210
Selling and marketing expense
Stock-based compensation expense by function:
Stock-based compensation expense	31,318	6,000	10,186
General and administrative expense
Stock-based compensation expense by function:
Stock-based compensation expense	192,957	77,151	82,798
Product development expense
Stock-based compensation expense by function:
Stock-based compensation expense	$ 38,462	$ 19,364	$ 11,256