NET INCOME PER SHARE ATTRIBUTABLE TO COMMON SHAREHOLDERS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income									$ 183,793	$ 159,106	$ 172,283
Net income attributable to holders of shares of common stock—diluted									$ 183,793	$ 159,106	$ 172,283
Denominator:
Weighted average shares of common stock outstanding—basic (in shares)									62,152,870	62,213,414	62,494,275
Weighted average number of incremental shares issuable from unvested restricted stock and restricted stock units, as calculated using the treasury stock method (in shares)									3,572,646	3,632,718	3,829,818
Weighted average shares of common stock outstanding—diluted (in shares)									65,725,516	65,846,132	66,324,093
Net income per share attributable to holders of shares of common stock
Basic (in usd per share)	$ 0.95	$ 0.79	$ 0.53	$ 0.69	$ 0.74	$ 0.71	$ 0.64	$ 0.47	$ 2.96	$ 2.56	$ 2.76
Diluted (in usd per share)	$ 0.90	$ 0.75	$ 0.50	$ 0.65	$ 0.69	$ 0.67	$ 0.61	$ 0.45	$ 2.80	$ 2.42	$ 2.60