Pension Plan - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Aug. 31, 2017	Feb. 28, 2018	Feb. 28, 2017
Defined Benefit Plan Disclosure [Line Items]
Employees covered under noncontributory Pension Plan	20.00%
Compensation period preceding retirement and termination	5 years
Period used for calculating Pension Plan liability	25 years
Expected contributions			$ 3,000,000
Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum required contribution to the plan is approximately		$ 0
Minimum [Member] | Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions		2,000,000
Maximum [Member] | Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions		$ 3,000,000