Stock-Based Incentive Plan - Compensation Expense Related to Stock Incentive Plans Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock-based compensation expense:
Total Expense	$ 594	$ 862
Tax benefit on nonqualified stock option expense, restricted stock awards and disqualifying dispositions of incentive stock options	165	243
Stock Options [Member]
Stock-based compensation expense:
Total Expense	216	228
Restricted Stock [Member]
Stock-based compensation expense:
Total Expense		619
Restricted Stock Awards and Restricted Stock Units [Member]
Stock-based compensation expense:
Total Expense	361
Employee Stock Purchase Plan [Member]
Stock-based compensation expense:
Total Expense	$ 17	$ 15