Derivative Instruments and Hedging Activities - Summary of Offsetting of Financial Assets and Derivative Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Net Amounts of Assets Presented in the Consolidated Balance Sheet	$ 9,752	$ 10,864
Interest rate swaps
Offsetting Assets [Line Items]
Gross Amount of Recognized Assets	5,930	4,723
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	5,930	4,723
Financial Instruments	0	0
Cash Collateral Received	5,070	0
Net Amount	$ 860	$ 4,723

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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