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Investments - Gross Unrealized Gains and Losses and Cost of Equity (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Equity securities, Cost	$ 24,457	$ 19,962
Equity securities, Gross Unrealized Gains	3,446	30
Equity securities, Gross Unrealized Losses		(1,341)
Equity securities, Fair Value	27,903	18,651
Domestic Common Stock [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Equity securities, Cost	24,457	19,962
Equity securities, Gross Unrealized Gains	3,446	30
Equity securities, Gross Unrealized Losses		(1,341)
Equity securities, Fair Value	$ 27,903	$ 18,651

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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