Percentage of voting equity interests acquired at the acquisition date in the business combination.

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- Definition

In a business combination achieved in stages, this element represents the amount of gain recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

+ References

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-SubTopic 10
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- Definition

Amount of hedged item in hedging relationship. Excludes hedged asset or liability.

+ References

No definition available.

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- Definition

Amount of decrease in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 3
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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
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-SubTopic 360
-Section 35
-Paragraph 11
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- Definition

The cash outflow for derivative instruments during the period, which are classified as investing activities, excluding those designated as hedging instruments.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
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- Definition

Gain on partial settlement and remeasurement of fair value of outstanding contingent consideration liabilities.

+ References

No definition available.

+ Details

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Gain on reduction of contingent consideration liabilities.

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No definition available.

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- Definition

Investments.

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No definition available.

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Balance Type:	na
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- Definition

Net realized gains (losses) during the period excluding amounts included in change in the fair value of equity securities and change in allowance for credit losses on available for sale securities.

+ References

No definition available.

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- Definition

Pre-tax loss from sale of privately held investment accounted under the equity method.

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No definition available.

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Amounts of Gross Realized Capital Gains and Gross Realized Capital Losses (Parenthetical) (Detail) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Apr. 01, 2020	Jul. 18, 2019	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020
Investments [Line Items]
Realized loss on early redemption of debt				$ (7,100)
Pre tax loss from sale of privately held investment accounted under equity method			$ 13,600		$ 13,600
Net realized capital gains				3,098	(6,551)	$ (3,241)
Put Option \| Equity Contract
Investments [Line Items]
Gross realized capital loss from derivative					38,400
Insurance Segment \| Ares
Investments [Line Items]
Net realized capital gains						45,700
Insurance Segment \| Put Option \| Equity Contract
Investments [Line Items]
Gross realized capital loss from derivative					$ 38,400
Cost of put option		$ 38,400
Portion of equity portfolio hedged for downside equity market risk		$ 1,000,000
Concord \| Alleghany Capital Corporation
Investments [Line Items]
Gain on partial settlement and remeasurement of fair value of outstanding contingent consideration liabilities				15,000
Wilbert Funeral Services, Inc
Investments [Line Items]
Gain on remeasurement of pre-existing equity ownership to estimated fair value	$ 16,300
Equity interest percentage acquired	55.00%
Equity interest percentage							45.00%
Precision Cutting Technologies, Inc
Investments [Line Items]
Realized gain on reduction of contingent consideration liabilities				5,000
Stranded Oil Resources Corporation
Investments [Line Items]
Write-down of oil field assets				$ 76,000		$ 35,400