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Retirement Plans - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]      
Expense of defined contribution retirement plans $ 978 $ 1,060 $ 1,338
Unfunded liability for supplemental plan $ 334 $ 802