Earnings per Common Share - Reconciliation of Number of Common Shares Used in Calculating Basic and Diluted Net Earnings Per Share (Detail) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Weighted Average Number of Shares Outstanding, Basic	16,595	16,539	16,581	16,531
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	188	0	107	0
Weighted Average Number of Shares Outstanding, Diluted	16,783	16,539	16,689	16,531
Basic net earnings per common share (in dollars per share)	$ 1.29	$ (0.66)	$ 3.29	$ (0.46)
Diluted net earnings per common share (in dollars per share)	$ 1.28	$ (0.66)	$ 3.27	$ (0.46)
Anti-dilutive shares excluded from calculation	400	1,100	600	1,000