Agreements and Transactions with Related Parties - Related Party Income (Details) - Affiliated Entity - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transaction
Distributions of Available Cash	$ 1,787	$ 2,029	$ 3,326	$ 3,945
Interest income on deferred acquisition fees and loans to affiliates	30	83	64	360
Revenue from related parties	6,751	8,995	13,319	25,601
Asset management and other revenue
Related Party Transaction
Gross contract revenue	3,966	4,472	7,920	14,361
Reimbursable costs from affiliates
Related Party Transaction
Gross contract revenue	968	2,411	2,009	6,441
Structuring and other advisory revenue
Related Party Transaction
Gross contract revenue	$ 0	$ 0	$ 0	$ 494

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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+ Details