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Derivative Instruments - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Period of LIBOR interest rate	30 days
Effective portion of gain/loss on derivatives included as a component of other comprehensive income, net of taxes	$ 309	$ 175	$ (270)
Other Assets [Member]
Derivative [Line Items]
Fair values of interest rate corridor instrument	600	509
Interest Rate Corridor [Member]
Derivative [Line Items]
Notional amount of derivative instrument	$ 60,000
Description of interest rate risk hedge at several thresholds	the Company pays variable interest monthly based on the 30-day LIBOR rates until that index reaches 1.5%. If 30-day LIBOR is equal to 1.5% through 3.0%, the Company pays 1.5%. If 30-day LIBOR exceeds 3.0%, the Company pays actual 30-day LIBOR less 1.5%.
Interest Rate Corridor [Member] | LIBOR
Derivative [Line Items]
Maximum percentage of variable interest rates based on LIBOR	1.50%
Percentage of amount paid by Company	1.50%
Percentage deducted from LIBOR for actual payment	1.50%
Interest Rate Corridor [Member] | LIBOR | Minimum
Derivative [Line Items]
Percentage of LIBOR	1.50%
Interest Rate Corridor [Member] | LIBOR | Maximum
Derivative [Line Items]
Percentage of LIBOR	3.00%
Cash Flow Hedging [Member]
Derivative [Line Items]
Effective portion of gain/loss on derivatives included as a component of other comprehensive income, net of taxes	$ 157	$ 17	$ 245

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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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Maximum percentage of variable interest rates based on base interest rate.

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- Definition

Fair value of credit risk derivative asset.

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-Topic 815
-SubTopic 10
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- Definition

Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.

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- Definition

General discussion of the entity's interest rate cash flow hedge activities.

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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