Retirement and Postretirement Benefit Plans (Defined Benefit Plan) - Additional Information (Detail) - USD ($)	12 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 28, 2014
Canadian Subsidiary [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of unfunded defined benefit pension plans	Two unfunded defined benefit plans, one that covers a supplemental executive retirement pension relating to an employment agreement and one that pays supplemental pensions to certain former hourly employees pursuant to a prior collective bargaining agreement.
Gibson Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer's contributions to defined benefit pension plan	$ 4,516,000	$ 3,518,000	$ 0
Estimated future employer contribution	4,900,000
Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in benefit obligation due to a change in control			2,613,000
Curtailment gain			7,164,000
Curtailment loss included in net periodic benefit cost			1,746,000
Estimated future employer contribution	2,550,000
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer's contributions to defined benefit pension plan	6,547,000	$ 5,612,000
Increase in benefit obligation due to a change in control			2,613,000
Curtailment gain			7,164,000
Curtailment loss included in net periodic benefit cost			$ 1,746,000
Estimated future amortization of net loss (gain)	3,474,000
Estimated future amortization of transition obligation	$ 4,000
Defined Benefit Pension Plans [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Description of unrecognized actuarial gains and losses amortized over percentage in excess of greater of benefit obligation or plan assets	Unrecognized actuarial gains and losses in excess of 10% of the greater of the benefit obligation or plan assets are amortized over the average remaining future service period of active participants or the life expectancy of inactive participants, as appropriate.
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future amortization of net loss (gain)	$ (1,470,000)
Estimated future amortization of prior service cost	$ (700,000)
Expected long-term return on plan assets	6.50%	6.50%
Postretirement Benefit Plan [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Description of unrecognized actuarial gains and losses amortized over percentage in excess of greater of benefit obligation or plan assets	The unrecognized net gain in excess of 10% of the greater of the benefit obligation or plan assets is amortized over the average future service period of active participants expected to receive benefits. Prior service credits are amortized straight-line beginning at the date of each plan amendment over the average future service period of the affected plan participants expected to receive benefits.