Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Federal statutory tax rate	21.00%	35.00%	35.00%
Restatement of deferred tax liability due to change in tax rate	$ 8,314,000	$ 7,650,000
Deferred tax amounts, valuation allowance recorded	0	0
Uncertain tax positions	$ 0	$ 0
Minimum [Member]
Income Taxes [Line Items]
Tax position measured if more-likely-than-not threshold is exceeded, percentage	50.00%

Income tax expense benefit cumulative amount of restatement of net deferred tax liability.

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- Definition

Income Taxes [Line Items]

+ References

No definition available.

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- Definition

Percentage of cumulative tax position.

+ References

No definition available.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

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- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

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-Topic 740
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-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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- Definition

Amount recognized for uncertainty in income taxes classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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