SEGMENT AND GEOGRAPHIC INFORMATION - REVENUE BY DISTRIBUTION CHANNEL (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Net revenue by distribution channel:
Net revenue	$ 450,274	$ 480,840	$ 443,562	$ 418,216	$ 571,555	$ 476,474	$ 420,167	$ 311,552	$ 1,792,892	$ 1,779,748	$ 1,413,698
Digital online
Net revenue by distribution channel:
Net revenue									1,130,946	921,734	697,658
Physical retail and other
Net revenue by distribution channel:
Net revenue									$ 661,946	$ 858,014	$ 716,040