Fair Value Measurements and Derivative Instruments - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Short-Term Borrowings	$ 844,083	$ 718,156
Short-Term Borrowings	844,083	718,156
Total	27,150,222	18,257,181
Total	27,043,081	18,239,934
Unamortized debt issuance costs	100,245	61,526
Bard Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,449,196	879,000
Fair Value	1,449,196	879,000
Castle Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,195,027	1,171,809
Fair Value	1,195,027	1,171,809
Maroon Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	800,000	483,952
Fair Value	800,000	483,952
Summit Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,535,572	1,643,154
Fair Value	1,535,572	1,643,154
Denali Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	749,800	668,400
Fair Value	749,800	668,400
Bushnell Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	600,000	395,500
Fair Value	600,000	395,500
Granite Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	562,700	248,000
Fair Value	562,700	248,000
Middle Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	599,950	799,550
Fair Value	599,950	799,550
Bison Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,467,300	1,320,800
Fair Value	1,467,300	1,320,800
Blanca Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,000,000	892,800
Fair Value	1,000,000	892,800
Windom Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,612,648	989,759
Fair Value	1,612,648	989,759
Monarch Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	1,123,400	567,400
Fair Value	1,123,400	567,400
Borah Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	381,000	0
Fair Value	381,000	0
Naomi Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	340,000	0
Fair Value	340,000	0
Meridian Peak Funding Facility
Debt Instrument [Line Items]
Net Carrying Value	100,000	0
Fair Value	100,000	0
2022-1 BSL WH
Debt Instrument [Line Items]
Net Carrying Value	168,000	0
Fair Value	168,000	0
Revolving Credit Facility
Debt Instrument [Line Items]
Net Carrying Value	1,543,710	1,144,422
Fair Value	1,543,710	1,144,422
June 2024 Notes
Debt Instrument [Line Items]
Net Carrying Value	413,517	431,854
Fair Value	415,757	431,738
Unamortized debt issuance costs	2,200	3,100
June 2026 Notes
Debt Instrument [Line Items]
Net Carrying Value	397,444	396,952
Fair Value	389,987	390,400
Unamortized debt issuance costs	2,500	3,000
September 2024 Notes
Debt Instrument [Line Items]
Net Carrying Value	344,879	361,805
Fair Value	347,189	359,232
Unamortized debt issuance costs	2,300	3,200
December 2026 Notes
Debt Instrument [Line Items]
Net Carrying Value	1,155,655	1,227,844
Fair Value	1,174,535	1,218,850
Unamortized debt issuance costs	19,600	22,200
November 2026 Eurobonds
Debt Instrument [Line Items]
Net Carrying Value	484,402	563,695
Fair Value	482,156	564,473
Unamortized debt issuance costs	6,100	6,300
November 2024 Notes
Debt Instrument [Line Items]
Net Carrying Value	470,872	496,054
Fair Value	473,960	499,946
Unamortized debt issuance costs	3,100	3,900
March 2027 Notes
Debt Instrument [Line Items]
Net Carrying Value	988,722	987,298
Fair Value	973,084	1,010,942
Unamortized debt issuance costs	11,300	12,700
January 2025 Notes
Debt Instrument [Line Items]
Net Carrying Value	469,326	0
Fair Value	472,810	0
Unamortized debt issuance costs	3,900
January 2029 Notes
Debt Instrument [Line Items]
Net Carrying Value	638,778	0
Fair Value	657,770	0
Unamortized debt issuance costs	11,200
March 2025 Notes
Debt Instrument [Line Items]
Net Carrying Value	852,378	0
Fair Value	859,293	0
Unamortized debt issuance costs	7,300
May 2027 Notes
Debt Instrument [Line Items]
Net Carrying Value	593,636	0
Fair Value	595,821	0
Unamortized debt issuance costs	2,500
April 2026 UK Bonds
Debt Instrument [Line Items]
Net Carrying Value	248,301	0
Fair Value	298,836	0
Unamortized debt issuance costs	3,100
September 2025 Notes
Debt Instrument [Line Items]
Net Carrying Value	590,541	0
Fair Value	599,441	0
Unamortized debt issuance costs	8,900
2021-1 BSL Debt
Debt Instrument [Line Items]
Net Carrying Value	661,975	661,910
Fair Value	663,000	663,148
Unamortized debt issuance costs	1,000	1,100
2022-1 BSL Debt
Debt Instrument [Line Items]
Net Carrying Value	418,376	0
Fair Value	419,311	0
Unamortized debt issuance costs	1,600
2021-2 Debt
Debt Instrument [Line Items]
Net Carrying Value	504,222	504,124
Fair Value	505,800	505,750
Unamortized debt issuance costs	1,600	1,700
MML 2021-1 Debt
Debt Instrument [Line Items]
Net Carrying Value	685,943	685,696
Fair Value	690,000	690,000
Unamortized debt issuance costs	4,200	4,300
MML 2022-1 Debt
Debt Instrument [Line Items]
Net Carrying Value	753,757	0
Fair Value	759,000	0
Unamortized debt issuance costs	5,300
MML 2022-2 Debt
Debt Instrument [Line Items]
Net Carrying Value	297,971	0
Fair Value	300,085	$ 0
Unamortized debt issuance costs	$ 2,500

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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