Long-Term Debt - Interest rates (Details) - Credit Agreement	3 Months Ended		9 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Minimum
Revolving Line of Credit
Interest rate range during each year (as a percent)	2.50%	2.00%	2.30%	1.90%
Maximum
Revolving Line of Credit
Interest rate range during each year (as a percent)	4.50%	4.30%	4.80%	4.30%