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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Weighted Average Number of Shares Outstanding, Basic	16,594	16,539	16,575	16,528
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	92	0	70	24
Weighted Average Number of Shares Outstanding, Diluted	16,686	16,539	16,644	16,552
Basic net earnings per common share (in dollars per share)	$ 1.37	$ (0.03)	$ 2.00	$ 0.21
Diluted net earnings per common share (in dollars per share)	$ 1.36	$ (0.03)	$ 1.99	$ 0.21
Anti-dilutive shares excluded from calculation	700	1,100	800	1,000