Derivatives - Fair Value Measurements on Recurring Basis (Detail) $ in Thousands	Jun. 30, 2015 USD ($)
Fair Value on Recurring Basis [Line Items]
Group I Swaps	$ (6,077)
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value on Recurring Basis [Line Items]
Group I Swaps	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value on Recurring Basis [Line Items]
Group I Swaps	(6,077)
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3)
Fair Value on Recurring Basis [Line Items]
Group I Swaps	$ 0