Offsetting Assets and Liabilities - Offsetting of Derivative Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives Asset
Gross Amounts of Recognized Assets	$ 26,385	$ 6,896
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts of Assets presented in the Condensed Consolidated Balance Sheets	26,385	6,896
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(105)	0
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Cash Collateral Received	(26,280)	(6,896)
Net Amount	$ 0	$ 0