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

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Percentage of equity interests of the surviving entity issued in consideration in a business merger.

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Number of shares of the surviving entity issued as consideration in a business merger.

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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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Ratio applied to the conversion of previous equity ownership shares to equity ownership shares in the surviving company in a business merger.

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Percentage of common stock retained by the principal shareholders which does not result in change in ownership change of fifty percent or more.

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The maximum amount of Net Operating Losses that can be utilized annually as limited by Sec 382 of the Internal Revenue Code due to ownership change.

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Number of shares sold by principal stockholders in an offering.

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Threshold percentage of stock of a corporation or any change in ownership arising from a new issuance of stock by the corporation.

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

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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

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Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant.

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

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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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Income Taxes - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended
	Aug. 15, 2019	Jul. 25, 2019	Jan. 01, 2018	Nov. 23, 2010	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Effective income tax rate					21.00%
Statutory income tax rate			21.00%				35.00%
Income taxes paid or (refund received)					$ (780)	$ 135	$ 227
Income tax recoverable included in other assets					$ 200	800	200
Ownership percentage					50.00%
Ownership Changes Among Shareholders					5.00%
Shares of the Company issued as merger consideration		38,851,369
Conversion ratio of PGHL shares to Company shares		6.46
Percentage of equity interests of the Company issued as merger consideration		100.00%
Percentage Of Outstanding Common Stock Retained	77.50%	80.30%
Shares Sold By Principal Stockholders In Offering	1,178,570
Valuation allowance					$ 17,604	16,962	6,511
Insurance Operations, U.K. \| Discontinued operation
Income Tax Disclosure [Line Items]
Income taxes paid or (refund received)						$ 0	$ 0
Gain (loss) recognized					$ 0
NYMAGIC, Inc
Income Tax Disclosure [Line Items]
Outstanding common stock acquired (as a percent)				100.00%
Cash price per share				$ 25.75
Cash price				$ 231,900
Annual limit on utilization of Net Operating Losses due to Section 382				9,000
Valuation allowance				$ 3,100