Fair Value Measurements - Financial Assets and Liabilities Valued on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Asset - current	$ 463	$ 388
Derivative Asset - noncurrent	950	368
Derivative Liability - current	(2,258)	(2,098)
Derivative Liability - noncurrent	(3,172)	(1,673)
Derivative Assets and Liabilities, Total	(4,017)	(3,015)
Significant Other Observable Inputs Level 2 Member
Derivatives, Fair Value [Line Items]
Derivative Asset - current	463	388
Derivative Asset - noncurrent	950	368
Derivative Liability - current	(2,258)	(2,098)
Derivative Liability - noncurrent	(3,172)	(1,673)
Derivative Assets and Liabilities, Total	$ (4,017)	$ (3,015)