Schedule of Financial Instruments Where Carrying Value and Fair Value Differ (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term obligations, excluding capital leases	$ 78.8
Fair Value, Inputs, Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term obligations, excluding capital leases	0
Fair Value Inputs Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term obligations, excluding capital leases	78.9
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term obligations, excluding capital leases	$ 0