Variable Interest Entity and Noncontrolling Interests - Other variable interest entity disclosures (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total VIE Assets		$ 47,990,507	$ 45,100,945	$ 43,282,297
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		3,904,776	3,248,206
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total VIE Assets		3,594,884	4,336,596
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		1,776	(4,434)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		26,800	42,202
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		28,576	37,768
Remaining Coverage, Amount		410,593
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2017-1 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		36,679	108,368
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(6)	(159)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		14	424
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		8	265
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2018-1 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		89,698	181,136
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(153)	(528)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		508	1,268
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		355	740
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2018-3 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		199,237	302,563
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(250)	(1,018)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		771	2,496
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		521	1,478
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-1 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		107,880	181,324
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(48)	(380)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		593	5,807
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		545	5,427
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-2 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		325,462	398,316
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(206)	(515)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		4,356	3,998
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		4,150	3,483
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-3 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		222,977	409,859
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(104)	(584)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		1,229	3,190
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		1,125	2,606
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-4 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		266,124	411,954
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(142)	(462)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		3,640	4,759
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		3,498	4,297
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2020-2 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		105,110	217,766
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		(8)	(177)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		492	1,984
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		484	1,807
Remaining Coverage, Amount	[1]	0
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2020-3 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		243,891	348,818
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		53	(128)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		2,872	5,793
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		2,925	5,665
Remaining Coverage, Amount	[1]	7,079
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2020-4 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		97,563	176,826
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		32	(50)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		642	1,630
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		674	1,580
Remaining Coverage, Amount	[1]	4,165
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2021-1 Ltd Member
Variable Interest Entity [Line Items]
Total VIE Assets		467,469	568,986
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		239	(303)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		2,743	3,283
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		2,982	2,980
Remaining Coverage, Amount	[1]	35,798
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2021-2 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		458,362	522,807
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		581	281
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		2,855	4,124
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		3,436	4,405
Remaining Coverage, Amount	[1]	77,099
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2021-3 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		489,927	507,873
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		217	(411)
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		2,704	3,446
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		2,921	$ 3,035
Remaining Coverage, Amount	[1]	127,032
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2022-01 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		283,500
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		399
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		1,765
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		2,164
Remaining Coverage, Amount	[1]	33,260
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2022-2 Ltd
Variable Interest Entity [Line Items]
Total VIE Assets		201,005
Variable Interest Entity, Maximum Exposure to Loss, On Balance Sheet, Asset (Liability) Net		1,172
Variable Interest Entity, Maximum Exposure to Loss, Off Balance Sheet		1,616
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		2,788
Remaining Coverage, Amount	[1]	$ 126,160

[1] Coverage from a separate panel of reinsurers remaining at December 31, 2022