Shareholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Preferred stock, shares outstanding	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	$ (72)	$ (141)	$ 82
Common Stock, Shares, Issued	15,200,435	15,135,598
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Authorized	5,000,000
Accumulated other comprehensive loss	$ (131)	$ (59)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	72	141	(82)
Pension and Other Postretirement Benefits Cost (Reversal of Cost)	100	100	100
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (310,629)	$ 70,448	$ 224,867