Summary of Significant Accounting Policies - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2017
Disaggregation of Revenue [Line Items]
Net sales	$ 202,548	$ 239,516	$ 222,787	$ 262,236	$ 200,660	$ 208,158	$ 196,329	$ 205,283	$ 927,087	$ 810,430	$ 863,538
Industrial [Member]
Disaggregation of Revenue [Line Items]
Net sales									526,465	461,945	518,123
Trasmission & Distribution [Member]
Disaggregation of Revenue [Line Items]
Net sales									212,433	194,503	164,072
Power Generation [Member]
Disaggregation of Revenue [Line Items]
Net sales									$ 188,189	$ 153,982	$ 181,343