Stock-based Compensation Plans - Summary of Change in Post Retirement Benefit Obligation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Changes in Benefit Obligations in Other Comprehensive Income (Loss):
Net loss (gain)	$ 532	$ (526)	$ 0
Prior service cost	0	0	1,769
Amortization of prior service cost	(369)	(369)	0
Other Post Retirement Benefits
Change in Benefit Obligation:
Benefit obligation at beginning of year	1,355	1,769
Prior service cost	0	0
Service cost	88	94
Interest cost	68	58
Actuarial loss (gain)	532	(526)
Benefits paid	(86)	(40)
Benefit obligation at end of year	1,957	1,355	$ 1,769
Amounts recognized in the consolidated balance sheet:
Long-term liabilities	1,957	1,355
Components of Net Periodic Post Retirement Benefit Cost:
Service cost	88	94
Interest cost	68	58
Amortization of prior service cost	369	369
Net periodic post retirement costs (recognized in general and administrative expense)	525	521
Other Changes in Benefit Obligations in Other Comprehensive Income (Loss):
Net loss (gain)	532	(526)
Prior service cost	0	0
Amortization of prior service cost	(369)	(369)
Total recognized in other comprehensive income (loss)	163	(895)
Total recognized in net periodic benefit cost and other comprehensive income (loss)	$ 688	$ (374)