Employee Benefit Plans - Summary of Amounts Expected to be Recognized in Net Periodic Cost in Coming Year (Detail) - USD ($) |
Dec. 31, 2017 |
Dec. 31, 2016 |
---|---|---|
Pension Plan [Member] | ||
Amounts Expected to be Recognized in Net Periodic Cost in the Coming Year | ||
(Gain) loss recognition | $ (992,724) | |
Prior service cost recognition | 0 | $ 0 |
Net initial obligation (asset) recognition | 0 | 0 |
Supplemental Employee Retirement Plan [Member] | ||
Amounts Expected to be Recognized in Net Periodic Cost in the Coming Year | ||
Prior service cost recognition | 0 | 0 |
Net initial obligation (asset) recognition | 0 | 0 |
Postretirement Benefits [Member] | ||
Amounts Expected to be Recognized in Net Periodic Cost in the Coming Year | ||
Prior service cost recognition | 0 | 0 |
Net initial obligation (asset) recognition | $ 0 | $ 0 |