New Accounting Pronouncements - Additional Information (Detail) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Retained earnings	$ 557,969,000	$ 479,576,000
Cumulative Effect Period Of Adoption Adjustment Member [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Retained earnings	$ 0

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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-Name Accounting Standards Codification
-Topic 210
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-SubTopic 10
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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