Fair Value of Financial Instruments - Unobservable Inputs (Details) $ in Millions	Sep. 30, 2022 USD ($)		Dec. 31, 2021 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 15,791.8	[1]	$ 16,101.0
Level 3—Significant unobservable inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	13,711.0		13,972.0
Level 3—Significant unobservable inputs | Senior Notes | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 9,513.0		$ 8,746.0
Level 3—Significant unobservable inputs | Senior Notes | Discounted Cash Flow | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.055		0.053
Level 3—Significant unobservable inputs | Senior Notes | Discounted Cash Flow | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.211		0.303
Level 3—Significant unobservable inputs | Senior Notes | Discounted Cash Flow | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.110		0.085
Level 3—Significant unobservable inputs | Senior Notes | Waterfall
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 580.0		$ 737.0
Level 3—Significant unobservable inputs | Senior Notes | Waterfall | EBITDA Multiple | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.3		0.1
Level 3—Significant unobservable inputs | Senior Notes | Waterfall | EBITDA Multiple | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	21.3		11.0
Level 3—Significant unobservable inputs | Senior Notes | Waterfall | EBITDA Multiple | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.7		7.0
Level 3—Significant unobservable inputs | Senior Notes | Cost
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 341.0		$ 1,242.0
Level 3—Significant unobservable inputs | Senior Notes | Other
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	108.0		51.0
Level 3—Significant unobservable inputs | Subordinated Debt | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 237.0
Level 3—Significant unobservable inputs | Subordinated Debt | Discounted Cash Flow | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.109
Level 3—Significant unobservable inputs | Subordinated Debt | Discounted Cash Flow | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.155
Level 3—Significant unobservable inputs | Subordinated Debt | Discounted Cash Flow | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.126
Level 3—Significant unobservable inputs | Subordinated Debt | Waterfall
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 17.0		$ 53.0
Level 3—Significant unobservable inputs | Subordinated Debt | Waterfall | EBITDA Multiple | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	5.8		7.0
Level 3—Significant unobservable inputs | Subordinated Debt | Waterfall | EBITDA Multiple | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	5.8		7.8
Level 3—Significant unobservable inputs | Subordinated Debt | Waterfall | EBITDA Multiple | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	5.8		7.8
Level 3—Significant unobservable inputs | Subordinated Debt | Cost
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value			$ 21.0
Level 3—Significant unobservable inputs | Asset Based Finance | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 859.0		$ 744.0
Level 3—Significant unobservable inputs | Asset Based Finance | Discounted Cash Flow | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.048		0.042
Level 3—Significant unobservable inputs | Asset Based Finance | Discounted Cash Flow | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.441		0.162
Level 3—Significant unobservable inputs | Asset Based Finance | Discounted Cash Flow | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.103		0.101
Level 3—Significant unobservable inputs | Asset Based Finance | Waterfall
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 686.0		$ 1,021.0
Level 3—Significant unobservable inputs | Asset Based Finance | Waterfall | EBITDA Multiple | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.0		1.0
Level 3—Significant unobservable inputs | Asset Based Finance | Waterfall | EBITDA Multiple | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	21.8		23.1
Level 3—Significant unobservable inputs | Asset Based Finance | Waterfall | EBITDA Multiple | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	3.4		4.1
Level 3—Significant unobservable inputs | Asset Based Finance | Cost
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 80.0		$ 359.0
Level 3—Significant unobservable inputs | Asset Based Finance | Other
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	197.0		117.0
Level 3—Significant unobservable inputs | Asset Based Finance | Indicative Dealer Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 4.0		$ 4.0
Level 3—Significant unobservable inputs | Asset Based Finance | Indicative Dealer Quotes | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.418		0.508
Level 3—Significant unobservable inputs | Asset Based Finance | Indicative Dealer Quotes | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.418		0.508
Level 3—Significant unobservable inputs | Asset Based Finance | Indicative Dealer Quotes | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.418		0.508
Level 3—Significant unobservable inputs | Equity/Other | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 352.0		$ 111.0
Level 3—Significant unobservable inputs | Equity/Other | Discounted Cash Flow | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.098		0.073
Level 3—Significant unobservable inputs | Equity/Other | Discounted Cash Flow | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.250		0.250
Level 3—Significant unobservable inputs | Equity/Other | Discounted Cash Flow | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.146		0.098
Level 3—Significant unobservable inputs | Equity/Other | Waterfall
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 599.0		$ 737.0
Level 3—Significant unobservable inputs | Equity/Other | Waterfall | EBITDA Multiple | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0		0.1
Level 3—Significant unobservable inputs | Equity/Other | Waterfall | EBITDA Multiple | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	15.0		16.0
Level 3—Significant unobservable inputs | Equity/Other | Waterfall | EBITDA Multiple | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	7.6		6.1
Level 3—Significant unobservable inputs | Equity/Other | Cost
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 127.0		$ 2.0
Level 3—Significant unobservable inputs | Equity/Other | Other
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	8.0		22.0
Level 3—Significant unobservable inputs | Equity/Other | Option Pricing Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3.0		$ 5.0
Level 3—Significant unobservable inputs | Equity/Other | Option Pricing Model | Equity Illiquidity Discount | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.650		0.650
Level 3—Significant unobservable inputs | Equity/Other | Option Pricing Model | Equity Illiquidity Discount | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.650		0.650
Level 3—Significant unobservable inputs | Equity/Other | Option Pricing Model | Equity Illiquidity Discount | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.650		0.650

[1] Security may be an obligation of one or more entities affiliated with the named company