TRANSACTION AND INTEGRATION RELATED COSTS IN CONNECTION WITH THE COMBINATION - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition
Stock-based compensation expense	$ 22,474	$ 103,980	$ 69,433	$ 120,280
Cost of revenue
Business Acquisition
Stock-based compensation expense		9		19
Selling and marketing expense
Business Acquisition
Stock-based compensation expense	868	19,709	2,526	20,402
General and administrative expense
Business Acquisition
Stock-based compensation expense	19,326	71,732	60,331	86,650
Product development expense
Business Acquisition
Stock-based compensation expense	2,280	12,530	6,576	13,209
Angie's List
Business Acquisition
Transaction and integration related costs	255	25,980	3,578	29,660
Stock-based compensation expense	16,039	96,938	51,868	96,938
Total	16,294	122,918	55,446	126,598
Accrual as of January 1			8,480
Charges incurred			3,578
Payments made			(10,757)
Accrual as of September 30	1,301		1,301
Angie's List | Cost of revenue
Business Acquisition
Transaction and integration related costs	0	0	0	0
Stock-based compensation expense	0	0	0	0
Total	0	0	0	0
Angie's List | Selling and marketing expense
Business Acquisition
Transaction and integration related costs	0	4,061	0	4,061
Stock-based compensation expense	550	19,510	1,650	19,510
Total	550	23,571	1,650	23,571
Angie's List | General and administrative expense
Business Acquisition
Transaction and integration related costs	255	21,619	3,578	25,299
Stock-based compensation expense	13,756	65,236	45,285	65,236
Total	14,011	86,855	48,863	90,535
Angie's List | Product development expense
Business Acquisition
Transaction and integration related costs	0	300	0	300
Stock-based compensation expense	1,733	12,192	4,933	12,192
Total	$ 1,733	$ 12,492	$ 4,933	$ 12,492