Amounts of Gross Realized Capital Gains and Gross Realized Capital Losses (Parenthetical) (Detail) $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($)
Investments [Line Items]
Realized loss on early redemption of debt	$ 7.1
Precision Cutting Technologies, Inc
Investments [Line Items]
Realized gain on reduction of contingent consideration liabilities	5.0
Stranded Oil Resources Corporation
Investments [Line Items]
Write-down of oil field assets	$ 30.0

The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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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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