Derivative Financial Instruments - Derivative Financial Instruments (Detail) - Derivatives Designated as Hedges [Member] - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Asset derivatives fair value	$ 3,543	$ 2,631
Liability derivatives fair value	1,307	9,365
Accounts receivable-other [Member]
Derivatives Fair Value [Line Items]
Asset derivatives fair value	3,543	2,631
Other liabilities [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	24	4
Accounts payable [Member]
Derivatives Fair Value [Line Items]
Liability derivatives fair value	$ 1,283	$ 9,361