The cash price per share paid to acquire voting equity interests at the acquisition date in the business combination.

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Amount of adjustments for changes in fair value of net assets acquired in a Business Combination.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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

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Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Goodwill and Intangibles - Acquisition of New York Marine (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 23, 2010	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business acquisition
Goodwill		$ 11,911	$ 11,911	$ 11,911
Intangible assets remaining to be amortized		$ 150
NYMAGIC
Business acquisition
Outstanding common stock acquired (as a percent)	100.00%
Cash price per share	$ 25.75
Cash price	$ 231,900
Fair value of net assets acquired	220,000
Fair value adjustments for net assets acquired	9,500
Goodwill	11,900
Intangible assets acquired, not subject to amortization	17,100
Intangible assets acquired, subject to amortization	13,600
Intangible assets remaining to be amortized	$ 200
NYMAGIC \| Minimum
Business acquisition
Intangible assets acquired, subject to amortization, amortization period	2 years
NYMAGIC \| Maximum
Business acquisition
Intangible assets acquired, subject to amortization, amortization period	15 years