Derivatives - Fair Value Measurements on Recurring Basis (Detail) $ in Thousands	Sep. 30, 2016 USD ($)
2014 Swaps
Derivatives, Fair Value [Line Items]
Fair Value	$ (11,410)
2014 Swaps | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Derivatives, Fair Value [Line Items]
Fair Value	0
2014 Swaps | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Derivatives, Fair Value [Line Items]
Fair Value	(11,410)
2014 Swaps | Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3)
Derivatives, Fair Value [Line Items]
Fair Value	0
2015 Swaps
Derivatives, Fair Value [Line Items]
Fair Value	(10,882)
2015 Swaps | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Derivatives, Fair Value [Line Items]
Fair Value	0
2015 Swaps | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Derivatives, Fair Value [Line Items]
Fair Value	(10,882)
2015 Swaps | Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3)
Derivatives, Fair Value [Line Items]
Fair Value	$ 0