Derivative Financial Instruments - Derivative Financial Instruments (Detail) - Derivatives Designated as Hedges [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives Fair Value [Line Items]
Asset derivatives fair value	$ 1,844	$ 2,298
Liability derivatives fair value	933	618
Accounts receivable-other [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	1,788	2,232
Other assets [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	56	66
Other liabilities [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	8
Accounts payable [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	$ 925	$ 618