Earnings Per Common Share - Additional Information (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Schedule Of Antidilutive Securities Included In Computation Of Earnings Per Share [Line Items]
Shares contingently issuable under shareholder return plan			14,640	0	0
Stock Option [Member]
Schedule Of Antidilutive Securities Included In Computation Of Earnings Per Share [Line Items]
Securities excluded from computation of net income per diluted shares	501,441	567,685	540,661	538,761
Restricted Stock [Member]
Schedule Of Antidilutive Securities Included In Computation Of Earnings Per Share [Line Items]
Shares contingently issuable under shareholder return plan			61,267	46,530