Derivative Instruments and Hedging Activities - Summary of Offsetting of Financial Liabilities and Derivative Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet	$ 10,074	$ 14,172
Interest rate swaps
Offsetting Assets [Line Items]
Gross Amount of Recognized Liabilities	5,058	9,825
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet	5,058	9,825
Financial Instruments	0	0
Cash Collateral Pledged	4,872	4,472
Net Amount	$ 186	$ 5,353

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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