Fair Value Measurements for Operating Entities and Consolidated Funds - Fair Value Inputs, Unobservable Inputs, Quantitative Information (Details) $ in Thousands		Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) times	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other investments		$ 237,628	$ 274,111
Quarton
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low		12,500	10,100
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		14,900	25,000
Portico
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low		0	0
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		58,000	58,000
Contingent liability payable
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Liability Value		57,339	62,223	$ 19,579	$ 37,952
Options (held long)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		228	234	241	251
Trade Claims
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		4,840	3,496	5,905	8,713
Warrants and Rights
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		18,557	15,403	7,924	6,547
Corporate Bonds
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		2,426	2,419	$ 136	$ 135
Level 3
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		241,383	182,501
Balance Liability Value		$ 60,418	$ 65,642
Level 3 | Contingent liability payable | Valuation Technique, Discounted Cash Flow | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.086	0.07
Level 3 | Contingent liability payable | Valuation Technique, Discounted Cash Flow | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.16	0.15
Level 3 | Contingent liability payable | Valuation Technique, Discounted Cash Flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.123	0.12
Level 3 | Contingent liability payable | Discount Cash Flow and Monte Carlo Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Liability Value		$ 57,339	$ 62,223
Level 3 | Contingent liability payable | Volatility | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.20	0.20
Level 3 | Contingent liability payable | Volatility | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.22	0.24
Level 3 | Contingent liability payable | Volatility | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.209	0.22
Level 3 | Common and Preferred Stock | Discounted Cash Flow and Market Approach Valuation Techniques
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		$ 75,253	$ 76,491
Level 3 | Common and Preferred Stock | Valuation Technique, Discounted Cash Flow | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.125	0.125
Level 3 | Common and Preferred Stock | Valuation Technique, Discounted Cash Flow | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.20	0.20
Level 3 | Common and Preferred Stock | Valuation Technique, Discounted Cash Flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.13	0.13
Level 3 | Common and Preferred Stock | Valuation, Market Approach | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		6.25	6.25
Level 3 | Common and Preferred Stock | Valuation, Market Approach | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		6.75	6.75
Level 3 | Common and Preferred Stock | Valuation, Market Approach | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		6.5	6.5
Level 3 | Options (held long) | Discounted Cash Flow and Market Approach Valuation Techniques
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		$ 228	$ 234
Level 3 | Options (held long) | Valuation Technique, Discounted Cash Flow | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.125	0.125
Level 3 | Options (held long) | Valuation Technique, Discounted Cash Flow | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.135	0.135
Level 3 | Options (held long) | Valuation Technique, Discounted Cash Flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.13	0.13
Level 3 | Trade Claims | Valuation Technique, Discounted Cash Flow
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		$ 2,138	$ 2,376
Level 3 | Warrants and Rights | Discounted Cash Flow and Market Approach Valuation Techniques
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		$ 5,986	$ 4,483
Level 3 | Warrants and Rights | Valuation Technique, Discounted Cash Flow | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.125	0.125
Level 3 | Warrants and Rights | Valuation Technique, Discounted Cash Flow | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.135	0.135
Level 3 | Warrants and Rights | Valuation Technique, Discounted Cash Flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.130	0.13
Level 3 | Warrants and Rights | Valuation, Market Approach | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.0625	0.0625
Level 3 | Warrants and Rights | Valuation, Market Approach | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.0675	0.0675
Level 3 | Warrants and Rights | Valuation, Market Approach | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.065	0.065
Level 3 | Warrants and Rights | Black Scholes Model | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.73	0.90
Level 3 | Warrants and Rights | Black Scholes Model | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		1.03	1
Level 3 | Warrants and Rights | Black Scholes Model | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.972	0.95
Level 3 | Other Investments
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value	[1]	$ 157,778	$ 98,917
Level 3 | Options (held long) | Valuation, Market Approach | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		6.25	6.25
Level 3 | Options (held long) | Valuation, Market Approach | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		6.75	6.75
Level 3 | Options (held long) | Valuation, Market Approach | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		6.5	6.5
Level 3 | Options (held short) | Valuation Technique, Discounted Cash Flow
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.0229
Level 3 | Options (held short) | Valuation Technique, Discounted Cash Flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.0229
Fair Value, Measurements, Recurring | Level 3 | Options (held short) | Derivative Liabilities | Valuation Technique, Option Pricing Model
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Liability Value		$ 3,079	$ 3,419
Discount rate | Level 3 | Trade Claims | Valuation Technique, Discounted Cash Flow
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.50	0.40
Discount rate | Level 3 | Trade Claims | Valuation Technique, Discounted Cash Flow | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.50	0.40
Volatility | Level 3 | Options (held short) | Valuation Technique, Option Pricing Model
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.35	0.35
Volatility | Level 3 | Options (held short) | Valuation Technique, Option Pricing Model | Weighted Average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Measurement Input		0.35	0.35

[1] The quantitative disclosures exclude financial instruments for which the determination of fair value is based on prices from recent transactions.