Variable Interest Entities and Noncontrolling Interests - Other variable interest entity disclosures (Details) - USD ($) $ in Thousands		Sep. 30, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Total VIE Assets		$ 46,337,104	$ 45,100,945
Maximum Exposure to Loss - Off-Balance Sheet		3,686,444	3,248,206
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total VIE Assets		3,824,794	4,336,596
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(11,216)	(4,434)
Maximum Exposure to Loss - Off-Balance Sheet		23,435	42,202
Maximum Exposure to Loss		12,219	37,768
Remaining Coverage, Amount		425,530
Variable Interest Entity, Not Primary Beneficiary | 2017-1 Ltd. (Oct-17)
Variable Interest Entity [Line Items]
Total VIE Assets		46,772	108,368
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(23)	(159)
Maximum Exposure to Loss - Off-Balance Sheet		88	424
Maximum Exposure to Loss		65	265
Variable Interest Entity, Not Primary Beneficiary | 2018-1 Ltd. (Apr-18)
Variable Interest Entity [Line Items]
Total VIE Assets		103,131	181,136
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(220)	(528)
Maximum Exposure to Loss - Off-Balance Sheet		644	1,268
Maximum Exposure to Loss		424	740
Variable Interest Entity, Not Primary Beneficiary | 2018-3 Ltd. (Oct-18)
Variable Interest Entity [Line Items]
Total VIE Assets		217,701	302,563
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(862)	(1,018)
Maximum Exposure to Loss - Off-Balance Sheet		2,107	2,496
Maximum Exposure to Loss		1,245	1,478
Variable Interest Entity, Not Primary Beneficiary | 2019-1 Ltd. (Mar-19)
Variable Interest Entity [Line Items]
Total VIE Assets		119,193	181,324
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(496)	(380)
Maximum Exposure to Loss - Off-Balance Sheet		2,704	5,807
Maximum Exposure to Loss		2,208	5,427
Variable Interest Entity, Not Primary Beneficiary | 2019-2 Ltd. (Apr-19)
Variable Interest Entity [Line Items]
Total VIE Assets		347,050	398,316
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(656)	(515)
Maximum Exposure to Loss - Off-Balance Sheet		4,308	3,998
Maximum Exposure to Loss		3,652	3,483
Variable Interest Entity, Not Primary Beneficiary | 2019-3 Ltd. (Jul-19)
Variable Interest Entity [Line Items]
Total VIE Assets		257,663	409,859
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(192)	(584)
Maximum Exposure to Loss - Off-Balance Sheet		1,492	3,190
Maximum Exposure to Loss		1,300	2,606
Variable Interest Entity, Not Primary Beneficiary | 2019-4 Ltd. (Oct-19)
Variable Interest Entity [Line Items]
Total VIE Assets		283,684	411,954
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(532)	(462)
Maximum Exposure to Loss - Off-Balance Sheet		3,663	4,759
Maximum Exposure to Loss		3,131	4,297
Variable Interest Entity, Not Primary Beneficiary | 2020-2 Ltd. (Sep-20)
Variable Interest Entity [Line Items]
Total VIE Assets		122,897	217,766
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(20)	(177)
Maximum Exposure to Loss - Off-Balance Sheet		595	1,984
Maximum Exposure to Loss		575	1,807
Remaining Coverage, Amount	[1]	153
Variable Interest Entity, Not Primary Beneficiary | 2020-3 Ltd. (Nov-20)
Variable Interest Entity [Line Items]
Total VIE Assets		268,385	348,818
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(204)	(128)
Maximum Exposure to Loss - Off-Balance Sheet		2,845	5,793
Maximum Exposure to Loss		2,641	5,665
Remaining Coverage, Amount	[1]	8,569
Variable Interest Entity, Not Primary Beneficiary | 2020-4 Ltd. (Dec-20)
Variable Interest Entity [Line Items]
Total VIE Assets		107,396	176,826
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		10	(50)
Maximum Exposure to Loss - Off-Balance Sheet		707	1,630
Maximum Exposure to Loss		717	1,580
Remaining Coverage, Amount	[1]	4,795
Variable Interest Entity, Not Primary Beneficiary | 2021-1 Ltd. (Mar-21)
Variable Interest Entity [Line Items]
Total VIE Assets		497,069	568,986
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(2,234)	(303)
Maximum Exposure to Loss - Off-Balance Sheet		936	3,283
Maximum Exposure to Loss		(1,298)	2,980
Remaining Coverage, Amount	[1]	43,198
Variable Interest Entity, Not Primary Beneficiary | 2021-2 Ltd. (Jun-21)
Variable Interest Entity [Line Items]
Total VIE Assets		471,039	522,807
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(2,047)	281
Maximum Exposure to Loss - Off-Balance Sheet		984	4,124
Maximum Exposure to Loss		(1,063)	4,405
Remaining Coverage, Amount	[1]	80,268
Variable Interest Entity, Not Primary Beneficiary | 2021-3 Ltd. (Sep-21)
Variable Interest Entity [Line Items]
Total VIE Assets		498,309	507,873
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(2,414)	(411)
Maximum Exposure to Loss - Off-Balance Sheet		991	3,446
Maximum Exposure to Loss		(1,423)	$ 3,035
Remaining Coverage, Amount	[1]	129,127
Variable Interest Entity, Not Primary Beneficiary | 2022-1 Ltd. (Jan-22)
Variable Interest Entity [Line Items]
Total VIE Assets		283,500
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		(1,326)
Maximum Exposure to Loss - Off-Balance Sheet		627
Maximum Exposure to Loss		(699)
Remaining Coverage, Amount	[1]	33,260
Variable Interest Entity, Not Primary Beneficiary | 2022-2 Ltd. (Sep-22)
Variable Interest Entity [Line Items]
Total VIE Assets		201,005
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability		0
Maximum Exposure to Loss - Off-Balance Sheet		744
Maximum Exposure to Loss		744
Remaining Coverage, Amount	[1]	$ 126,160

[1] Coverage from a separate panel of reinsurers remaining at September 30, 2022.