Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value, liabilities measured on recurring basis, derivative financial instruments, liabilities	$ 4,148	$ 4,070
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value, liabilities measured on recurring basis, derivative financial instruments, liabilities	4,148	4,070
Interest Rate Swap Agreements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value, liabilities measured on recurring basis, derivative financial instruments, liabilities	4,148	4,070
Interest Rate Swap Agreements | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value, liabilities measured on recurring basis, derivative financial instruments, liabilities	$ 4,148	$ 4,070