QUARTERLY FINANCIAL INFORMATION (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
QUARTERLY FINANCIAL INFORMATION (unaudited)
Revenues	$ 87,658	$ 116,459	$ 136,670	$ 141,366	$ 169,578	$ 232,945	$ 259,803	$ 230,489	$ 482,153	$ 892,815	$ 675,047
Gross profit	6,746	29,532	30,708	15,452	20,104	37,718	51,407	40,096	82,438	149,325	146,711
Income from operations	(4,293)	18,385	20,330	5,815	8,163	27,599	40,608	30,607	40,237	106,977	112,254
Net income (loss)	$ (2,207)	$ 32,434	$ 16,972	$ 4,837	$ 7,018	$ 17,229	$ 27,139	$ 20,625	$ 52,036	$ 72,011	$ 70,328
Earnings per share
Basic (in Dollars per share)	$ (0.14)	$ 2.08	$ 1.09	$ 0.31	$ 0.45	$ 1.11	$ 1.75	$ 1.33	$ 3.34	$ 4.64	$ 4.67
Diluted (in Dollars per share)	$ (0.14)	$ 2.07	$ 1.08	$ 0.31	$ 0.45	$ 1.09	$ 1.72	$ 1.31	$ 3.32	$ 4.56	$ 4.50