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.

No definition available.

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

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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- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Acquisitions, Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 44,695	$ 44,695
Impairment of goodwill	$ 44,700	$ 0	$ 0
Weighted average period to amortize acquired intangible assets		13 years
Commercial Accounts business unit [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 2,100
Aerospace & Programs business unit [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		9,700
Commercial Auto business units [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		21,300
E&S Casualty business unit [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		6,300
Public Entity Component [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		2,600
E & S Package component [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		3,700
Personal Lines Business Unit [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 5,300