Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Aug. 28, 2015	Aug. 29, 2014	Aug. 28, 2015	Aug. 29, 2014	Feb. 28, 2015
Income Taxes [Line Items]
Effective tax rate	21.00%	33.80%	31.70%	26.00%
Unrecognized tax benefit due to the issuance of regulations that clarified the law and the expiration of statute	$ 4.3		$ 4.3
Federal tax refund				$ 3.1
Tax on unrealized investment gains (losses) accounted for in other comprehensive income			22.0
Unrecognized tax benefits	16.9		16.9
Effect on income tax expense if unrecognized tax benefits are recognized	15.3		$ 15.3
Unrecognized tax benefits income tax penalties and interest accrued description			The Corporation recognizes interest and penalties accrued on unrecognized tax benefits and refundable income taxes as a component of income tax expense.
Interest and penalties on unrecognized tax benefits and refundable income taxes			$ 1.2
Accrued Interest and penalties on unrecognized tax benefit	$ 1.6		$ 1.6
Adjustments for Error Correction [Member]
Income Taxes [Line Items]
Reduction in income tax expense				$ 4.1	$ 4.1