Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2013	Feb. 29, 2012
Commitments and Contingencies [Line Items]
Letter of credit secure for environmental loss contingencies	$ 1.1
Reserve for environmental legal proceedings	1.2	1.2
Superfund
Commitments and Contingencies [Line Items]
Letter of credit secure for environmental loss contingencies	1.0
Estimated , site contingency liability	0.8
Lake Calumet Cluster
Commitments and Contingencies [Line Items]
Estimated , site contingency liability	0.3
Chatham
Commitments and Contingencies [Line Items]
Estimated , site contingency liability	$ 0.1
California Environmental Protection Agency
Commitments and Contingencies [Line Items]
Number of CEPA agencies	2