Secured Debt Arrangements, Net - Weighted Average Maturities and Interest Rates of Borrowings (Details) kr in Thousands, € in Millions, £ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2022 GBP (£)	Mar. 31, 2022 EUR (€)	Mar. 31, 2022 SEK (kr)	Jan. 31, 2022 USD ($)	Dec. 31, 2021 SEK (kr)	Jun. 30, 2020 USD ($)	Nov. 30, 2017 USD ($)
Debt Instrument [Line Items]
Percentage of secured debt that is recourse debt	52.00%	50.00%	52.00%	52.00%	52.00%		50.00%
Line of Credit
Debt Instrument [Line Items]
Maximum Amount of Borrowings	$ 5,342,032,000	$ 4,932,049,000
Borrowings outstanding	4,571,314,000	4,150,268,000
Less: deferred financing costs	$ (10,705,000)	$ (9,062,000)
Line of Credit | Weighted Average
Debt Instrument [Line Items]
Weighted average advance rate	70.50%	69.80%
Line of Credit | London Interbank Offered Rate (LIBOR) | Weighted Average
Debt Instrument [Line Items]
Weighted average rate	2.08%	2.00%
Line of Credit | GBP London Interbank Offered Rate (LIBOR) | Weighted Average
Debt Instrument [Line Items]
Weighted average rate	1.82%	1.86%
Line of Credit | EUR London Interbank Offered Rate (LIBOR) | Weighted Average
Debt Instrument [Line Items]
Weighted average rate	1.49%	1.42%
Line of Credit | SEK London Interbank Offered Rate (LIBOR) | Weighted Average
Debt Instrument [Line Items]
Weighted average rate	1.50%	1.50%
Line of Credit | JP Morgan Chase, DB Repurchase Facility, Goldman Sachs, Credit Suisse and HSBC Facilities
Debt Instrument [Line Items]
Maximum Amount of Borrowings	$ 3,409,366,000	$ 3,029,365,000
Borrowings outstanding	2,649,353,000	2,256,646,000
Line of Credit | Deutsche Bank Repurchase Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings						$ 700,000,000
Borrowings outstanding	421,500,000
Line of Credit | Goldman Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	300,000,000								$ 500,000,000
Borrowings outstanding	159,600,000
Line of Credit | Barclays Securitization
Debt Instrument [Line Items]
Borrowings outstanding			£ 925.4	€ 448.7	kr 2,100,000
Line of Credit | JP Morgan Chase, DB Repurchase Facility, Goldman Sachs, Credit Suisse, Barclays Facility, HSBC Facilities And Barclays Securitization
Debt Instrument [Line Items]
Maximum Amount of Borrowings	5,342,032,000	4,932,049,000
Borrowings outstanding	$ 4,582,019,000	$ 4,159,330,000
USD | Line of Credit | Weighted Average
Debt Instrument [Line Items]
Weighted average advance rate	66.50%	67.10%
USD | Line of Credit | JP Morgan Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	$ 1,415,051,000	$ 1,344,283,000
Borrowings outstanding	1,269,796,000	1,329,923,000
USD | Line of Credit | Deutsche Bank Repurchase Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	700,000,000	700,000,000
Borrowings outstanding	421,461,000	259,073,000
USD | Line of Credit | Goldman Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	300,000,000	300,000,000
Borrowings outstanding	159,618,000	168,231,000
USD | Line of Credit | Credit Suisse Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	486,319,000	161,609,000
Borrowings outstanding	470,651,000	148,720,000
USD | Line of Credit | Barclays Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	200,000,000	200,000,000
Borrowings outstanding	$ 32,693,000	$ 32,693,000
Fx contracts - GBP | Line of Credit
Debt Instrument [Line Items]
Currency conversion rate	1.31	1.35	1.31	1.31	1.31		1.35
Fx contracts - GBP | Line of Credit | Weighted Average
Debt Instrument [Line Items]
Weighted average advance rate	72.90%	72.70%
Fx contracts - GBP | Line of Credit | JP Morgan Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	$ 84,949,000	$ 87,497,000
Borrowings outstanding	$ 84,320,000	$ 86,849,000
Fx contracts - EUR | Line of Credit
Debt Instrument [Line Items]
Currency conversion rate	1.11	1.14	1.11	1.11	1.11		1.14
Fx contracts - EUR | Line of Credit | Weighted Average
Debt Instrument [Line Items]
Weighted average advance rate	75.60%	68.90%
Fx contracts - EUR | Line of Credit | JP Morgan Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	$ 0	$ 68,220,000
Borrowings outstanding	0	68,220,000
Fx contracts - EUR | Line of Credit | HSBC Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	163,285,000	167,756,000
Borrowings outstanding	158,592,000	162,937,000
Fx contracts - EUR | Line of Credit | Santander Facility
Debt Instrument [Line Items]
Maximum Amount of Borrowings	59,800,000	0		€ 54.0
Borrowings outstanding	$ 52,222,000	$ 0
Kronor | Line of Credit
Debt Instrument [Line Items]
Currency conversion rate	0.11	0.11	0.11	0.11	0.11		0.11
Kronor | Line of Credit | Weighted Average
Debt Instrument [Line Items]
Weighted average advance rate	80.70%	80.70%
VIE | Line of Credit | Barclays Securitization
Debt Instrument [Line Items]
Maximum Amount of Borrowings	$ 1,932,666,000	$ 1,902,684,000
Borrowings outstanding	1,932,666,000	1,902,684,000						$ 782,000,000
VIE | Line of Credit | Barclays Securitization | Weighted Average
Debt Instrument [Line Items]
Borrowings outstanding	1,932,666,000	1,902,683,000
VIE | Fx contracts - GBP | Line of Credit | Barclays Securitization | Weighted Average
Debt Instrument [Line Items]
Borrowings outstanding	1,215,814,000	1,299,321,000
VIE | Fx contracts - EUR | Line of Credit | Barclays Securitization | Weighted Average
Debt Instrument [Line Items]
Borrowings outstanding	$ 496,625,000	$ 373,904,000
VIE | Kronor | Line of Credit | Barclays Securitization | Weighted Average
Debt Instrument [Line Items]
Borrowings outstanding | kr					kr 220,227		kr 229,458