Stock-Based Incentive Plan - Compensation Expense Related to Stock Incentive Plans Recognized (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Stock-based compensation expense:
Total Expense	$ 1,292	$ 1,753
Tax benefit on nonqualified stock option expense, restricted stock awards and disqualifying dispositions of incentive stock options	284	413
Stock Options [Member]
Stock-based compensation expense:
Total Expense	378	515
Restricted Stock [Member]
Stock-based compensation expense:
Total Expense		1,204
Restricted Stock Awards and Restricted Stock Units [Member]
Stock-based compensation expense:
Total Expense	878
Employee Stock Purchase Plan [Member]
Stock-based compensation expense:
Total Expense	$ 36	$ 34