Borrowings - Debt Securitizations (Details) - USD ($)		12 Months Ended
	Jun. 29, 2021	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 11, 2024	Mar. 13, 2024	Dec. 13, 2023	Aug. 12, 2022	Jun. 09, 2022	Mar. 15, 2022	Dec. 15, 2021	Nov. 01, 2021
Debt Instrument [Line Items]
Aggregate Principal Committed		$ 36,809,690,000	$ 35,719,459,000
Borrowings on debt		12,405,681,000	3,684,216,000	$ 20,297,052,000
2021-1 BSL Notes
Debt Instrument [Line Items]
Outstanding Principal		819,500,000
2021-1 BSL Notes | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed	$ 876,600,000	663,000,000	663,000,000
Borrowings on debt	819,500,000
Outstanding Principal		$ 663,000,000	663,000,000
Increase in rate		0.26161%
2021-1 BSL Notes | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 156,500,000
2021-1 BSL, Senior Secured Floating Rate, Class A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 499,800,000
Applicable margin rate		1.25%
2021-1 BSL, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 38,760,000
Applicable margin rate		1.80%
2021-1 BSL, Mezzanine Secured Deferrable Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 59,160,000
Applicable margin rate		2.15%
2021-1 BSL, Mezzanine Secured Deferrable Floating Rate, Class D Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 65,280,000
Applicable margin rate		3.35%
2021-1 BSL, Junior Secured Deferrable Floating Rate | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed	$ 57,100,000
Outstanding Principal		$ 0
Applicable margin rate		7.00%
2021-2 Notes
Debt Instrument [Line Items]
Outstanding Principal		$ 603,650,000
2021-2 Notes | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed		505,800,000	505,800,000									$ 603,700,000
Outstanding Principal		$ 505,800,000	505,800,000
Increase in rate		0.26161%
2021-2 Notes | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 97,850,000
2021-2 Debt, Senior Secured Floating Rate, Class A-L Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 218,000,000
Applicable margin rate		1.22%
Increase (decrease) in principal amount		$ 0
2021-2 Debt, Senior Secured Floating Rate, Class A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 149,500,000
Applicable margin rate		1.22%
Increase (decrease) in principal amount		$ 218,000,000
2021-2 Notes, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 38,100,000
Applicable margin rate		1.75%
2021-2 Notes, Mezzanine Secured Deferrable Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 48,000,000
Applicable margin rate		2.05%
2021-2 Notes, Mezzanine Secured Deferrable Floating Rate, Class D Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 52,200,000
Applicable margin rate		3.15%
2021-1 MML Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 1,001,000,000
2021-1 MML Debt | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed											$ 1,000,000,000.0
Outstanding Principal		$ 690,000,000
Increase in rate		0.26161%
2021-1 MML Debt | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 311,000,000
2021-1 MML Debt, Senior Secured Floating Rate, Class A Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 50,000,000
Applicable margin rate		1.48%
2021-1 MML Debt, Senior Secured Floating Rate, Class A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 480,000,000
Applicable margin rate		1.48%
Increase (decrease) in principal amount		$ 50,000,000.0
2021-1 MML Debt, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 80,000,000
Applicable margin rate		1.90%
2021-1 MML Debt, Mezzanine Secured Deferrable Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 80,000,000
Applicable margin rate		2.60%
2022-1 MML Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 1,090,360,000
2022-1 MML Debt | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed										$ 1,100,000,000
Outstanding Principal		759,000,000
2022-1 MML Debt | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		331,360,000
2022-1 MML Debt, Senior Secured Floating Rate, Class A-1 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 525,000,000
Applicable margin rate		1.65%
2022-1 MML Debt, Senior Secured Fixed, Class A-2 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 80,000,000
Interest rate		3.41%
2022-1 MML Debt, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 66,000,000
Applicable margin rate		2.00%
2022-1 MML Debt, Mezzanine Secured Deferrable Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 88,000,000
Applicable margin rate		2.75%
2022-1 BSL Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 589,750,000
2022-1 BSL Debt | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed		420,000,000	420,000,000						$ 589,800,000
Outstanding Principal		531,000,000
2022-1 BSL Debt | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		58,750,000
2022-1 BSL Debt, Senior Secured Floating Rate, Class A-1A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 292,000,000
Applicable margin rate		1.58%
2022-1 BSL Debt, Senior Secured Fixed Rate, Class A-1B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 50,000,000
Interest rate		4.34%
2022-1 BSL Debt, Senior Secured Floating Rate, Class A-2 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 12,000,000
Applicable margin rate		2.00%
2022-1 BSL Debt, Senior Secured Floating Rate, Class B-1 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 40,000,000
Applicable margin rate		2.35%
2022-1 BSL Debt, Senior Secured Fixed Rate, Class B-2 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 26,000,000
Interest rate		4.98%
2022-1 BSL Debt, Secured Deferrable Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 51,000,000
Applicable margin rate		2.60%
2022-1 BSL Debt, Mezzanine Secured Deferrable Floating Rate, Class D Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 39,000,000
Applicable margin rate		3.69%
2022-1 BSL Debt, Mezzanine Secured Deferrable Floating Rate, Class E Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 21,000,000
Applicable margin rate		7.33%
MML 2022-2 Debt
Debt Instrument [Line Items]
Outstanding Principal		$ 498,105,000						$ 498,100,000
MML 2022-2 Debt | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed		300,500,000	300,500,000
Outstanding Principal		341,000,000
MML 2022-2 Debt | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		157,105,000
MML 2022-2 Debt, Senior Secured Floating Rate, Class A-L Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 275,000,000
Applicable margin rate		2.10%
MML 2022-2 Debt, Senior Secured Floating Rate, Class B-1 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 14,000,000
Applicable margin rate		3.35%
MML 2022-2 Debt, Senior Secured Fixed Rate, Class B-2 Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 11,500,000
Interest rate		5.88%
MML 2022-2 Debt, Mezzanine Secured Deferrable Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 40,500,000
Applicable margin rate		2.50%
2023-1 Notes
Debt Instrument [Line Items]
Outstanding Principal		$ 492,665,000					$ 492,700,000
2023-1 Notes | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed		305,000,000	$ 305,000,000
Outstanding Principal		339,000,000
2023-1 Notes | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		153,665,000
2023-1 CLO Debt, Senior Secured Floating Rate, Class A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 272,500,000
Applicable margin rate		2.30%
2023-1 CLO Debt, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 32,500,000
Applicable margin rate		3.00%
2023-1 CLO Debt, Senior Secured Floating Rate, Class C Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 34,000,000
Applicable margin rate		4.00%
2024-1 Notes
Debt Instrument [Line Items]
Outstanding Principal		$ 402,161,000				$ 402,200,000
2024-1 Notes | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed		244,000,000
Outstanding Principal		272,000,000
2024-1 Notes | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		130,161,000
2024-1 CLO Debt, Senior Secured Floating Rate, Class A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 180,000,000
Applicable margin rate		1.83%
2024-1 CLO Debt, Senior Secured Floating Rate, Class A-L Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 40,000,000
Applicable margin rate		1.83%
Increase (decrease) in principal amount		$ 220,000,000.0
2024-1 CLO Debt, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 24,000,000
Applicable margin rate		2.35%
2024-1 CLO Debt, Mezzanine Secured Deferrable Floating Rate, Class Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 28,000,000
Applicable margin rate		2.80%
2024-2 Notes
Debt Instrument [Line Items]
Outstanding Principal		$ 500,500,000			$ 500,500,000
2024-2 Notes | Secured debt
Debt Instrument [Line Items]
Aggregate Principal Committed		305,000,000
Outstanding Principal		340,000,000
2024-2 Notes | Subordinated Debt
Debt Instrument [Line Items]
Outstanding Principal		160,500,000
2024-2 CLO Debt, Senior Secured Floating Rate, Class A Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 60,000,000
Applicable margin rate		1.50%
Increase (decrease) in principal amount		$ 145,000,000.0
2024-2 CLO Debt, Senior Secured Floating Rate, Class A-L1 Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 145,000,000
Applicable margin rate		1.50%
Increase (decrease) in principal amount		$ (145,000,000.0)
2024-2 CLO Debt, Senior Secured Floating Rate, Class A-L2 Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 50,000,000
Applicable margin rate		1.50%
2024-2 CLO Debt, Senior Secured Floating Rate, Class A-L3 Loans | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 20,000,000
Applicable margin rate		1.50%
Increase (decrease) in principal amount		$ (20,000,000.0)
2024-2 CLO Debt, Senior Secured Floating Rate, Class B Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 30,000,000
Applicable margin rate		1.80%
2024-2 CLO Debt, Mezzanine Secured Deferrable Floating Rate, Class Notes | Secured debt
Debt Instrument [Line Items]
Outstanding Principal		$ 35,000,000
Applicable margin rate		2.00%