Derivatives - Fair Value Measurements on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Fair Value On Recurring Basis [Line Items]
Fair Value of Liabilities	$ (826)
Fair Value, Measurements Recurring Basis [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value On Recurring Basis [Line Items]
Fair Value of Liabilities	0
Fair Value, Measurements Recurring Basis [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value On Recurring Basis [Line Items]
Fair Value of Liabilities	0
Fair Value, Measurements Recurring Basis [Member] | Unobservable Inputs (Level 3) [Member]
Fair Value On Recurring Basis [Line Items]
Fair Value of Liabilities	$ (826)