Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
Jun. 30, 2019
Shares Under Option
Shares Under Option, Outstanding, Beginning balance	597,405
Shares Under Option, Expired	(9,756)
Shares Under Option, Forfeited	(8,000)
Shares Under Option, Exercised	(39,500)
Share Under Option, Outstanding, Ending balance	540,149
Shares Under Options, Exercisable at June 30, 2019	373,220
Weighted Average Exercise Price Per Share [Abstract]
Weighted Average Exercise Price Per Share, Outstanding, Beginning balance	$ 23.98
Weighted Average Exercise Price Per Share, Expired	23.61
Weighted Average Exercise Price Per Share, Forfeited	26.06
Weighted Average Exercise Price Per Share, Exercised	17.48
Weighted Average Exercise Price Per Share, Outstanding, Ending balance	24.44
Weighted Average Exercise Price Per Share, Exercisable at June 30, 2019	$ 22.72
Weighted Average Remaining Contractual Life, Outstanding at June 30, 2019	7 years
Weighted Average Remaining Contractual Life, Exercisable at June 30, 2019	6 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding at June 30, 2019	$ 1,658
Aggregate Intrinsic Value, Exercisable at June 30, 2019	$ 1,644

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.