Acquisition (Amortization Expense) (Details) - Cowen Insurance $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)
Business Acquisition [Line Items]
Amortization of Intangible Assets	$ 100	$ 300
Scenario, Plan
Business Acquisition [Line Items]
2021	114	114
2022	458	458
2023	458	458
2024	458	458
2025	458	458
Finite-Lived Intangible Asset, Expected Amortization, after Year Five	2,365	2,365
Finite-Lived Intangible Assets, Net	$ 4,311	$ 4,311

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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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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