STOCKHOLDERS' EQUITY (Schedule of Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation recorded to (loss) income before income taxes	$ 31,750	$ 31,319
Benefit from income taxes	(12,557)	(8,113)
Total stock-based compensation recorded to net (loss) income	19,193	23,206
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation recorded to (loss) income before income taxes	1,043	1,244
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation recorded to (loss) income before income taxes	7,696	7,687
Product development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation recorded to (loss) income before income taxes	17,755	16,075
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation recorded to (loss) income before income taxes	$ 5,256	$ 6,313