Income Taxes - Additional Information (Detail)	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) subsidiary	Dec. 31, 2018 USD ($)
Income Tax Disclosure [Abstract]
Number of subsidiaries subject to corporate tax \| subsidiary			8
Net operating losses carryback period			2 years
Capital losses carryback period			3 years
Change in valuation allowance	$ 0	$ (700,000)	$ (600,000)	$ (3,400,000)
Unrecognized tax benefits	$ 0	$ 0	$ 0

Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=116821951&loc=d3e32123-109318

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration