Secured Borrowings (Details) $ in Thousands, € in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2021 EUR (€)	Dec. 31, 2020 USD ($)
Secured borrowings and promissory note
Pledged Assets Carrying Value	$ 3,282,170		$ 1,693,520
Carrying Value, Secured borrowings	2,517,600		1,294,243
Secured borrowings
Secured borrowings and promissory note
Current facility size	4,098,351
Pledged Assets Carrying Value	3,282,170
Carrying Value, Secured borrowings	2,517,600		1,294,243
Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	1,145,170
Pledged Assets Carrying Value	576,777		557,215
Carrying Value, Secured borrowings	$ 471,883		$ 466,674
Weighted average interest rate of borrowings (as a percent)	2.80%	2.80%	3.00%
Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 2,953,181
Pledged Assets Carrying Value	2,705,393		$ 1,136,305
Carrying Value, Secured borrowings	$ 2,045,717		$ 827,569
Weighted average interest rate of borrowings (as a percent)	2.10%	2.10%	3.30%
Paycheck Protection Program loans
Secured borrowings and promissory note
Carrying Value, Secured borrowings	$ 941,505		$ 76,276
Purchased future receivables | Borrowings under credit facilities
Secured borrowings and promissory note
Pledged Assets Carrying Value	7,872
JPMorgan | Acquired SBA Loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	200,000
Pledged Assets Carrying Value	77,534
Carrying Value, Secured borrowings	$ 54,164		36,604
JPMorgan | Acquired SBA Loans | Borrowings under credit facilities | One Month LIBOR | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.50%
JPMorgan | Acquired SBA Loans | Borrowings under credit facilities | One Month LIBOR | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.875%
JPMorgan | Transitional loans | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 1,000,000
Pledged Assets Carrying Value	1,079,368
Carrying Value, Secured borrowings	$ 825,265		247,616
JPMorgan | Transitional loans | Borrowings under repurchase agreements | One Month LIBOR | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.00%
JPMorgan | Transitional loans | Borrowings under repurchase agreements | One Month LIBOR | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.75%
JPMorgan | Mortgage backed securities | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 83,267
Pledged Assets Carrying Value	107,837
Carrying Value, Secured borrowings	$ 83,267		65,407
JPMorgan | Mortgage backed securities | Borrowings under repurchase agreements | Minimum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	1.15%	1.15%
JPMorgan | Mortgage backed securities | Borrowings under repurchase agreements | Maximum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	1.71%	1.71%
Performance Trust | Acquired loans | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 239,000
Pledged Assets Carrying Value	142,722
Carrying Value, Secured borrowings	$ 124,057
Performance Trust | Acquired loans | Borrowings under repurchase agreements | One Month Treasury Rate
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.00%
Keybank | Freddie Mac Loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 100,000
Pledged Assets Carrying Value	42,384
Carrying Value, Secured borrowings	$ 41,864		50,408
Keybank | Freddie Mac Loans | Borrowings under credit facilities | Secured Overnight Financing Rate
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	1.41%
East West Bank | SBA loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 75,000
Pledged Assets Carrying Value	80,556
Carrying Value, Secured borrowings	$ 58,622		40,542
East West Bank | SBA loans | Borrowings under credit facilities | Administrative agent's prime rate | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	(0.821%)
East West Bank | SBA loans | Borrowings under credit facilities | Administrative agent's prime rate | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	0.00%
East West Bank | Residential MSRs | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 50,000
Pledged Assets Carrying Value	86,714
Carrying Value, Secured borrowings	$ 49,400		34,400
East West Bank | Residential MSRs | Borrowings under credit facilities | One Month LIBOR
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.50%
Credit Suisse | Acquired loans (non USD) | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 227,400	€ 200.0
Pledged Assets Carrying Value	46,154
Carrying Value, Secured borrowings	$ 40,373		36,840
Credit Suisse | Acquired loans (non USD) | Borrowings under credit facilities | Euribor Rate | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.50%
Credit Suisse | Acquired loans (non USD) | Borrowings under credit facilities | Euribor Rate | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	3.00%
Credit Suisse | Residential loans | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 63,412
Pledged Assets Carrying Value	32,779
Carrying Value, Secured borrowings	$ 27,058
Credit Suisse | Residential loans | Borrowings under repurchase agreements | LIBOR
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	3.00%
Credit Suisse | Purchased future receivables | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 50,000
Pledged Assets Carrying Value	7,872
Carrying Value, Secured borrowings	$ 1,000
Credit Suisse | Purchased future receivables | Borrowings under credit facilities | One Month LIBOR
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	4.50%
Credit Suisse | Fixed rate, Transitional, Acquired loans | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 500,000
Pledged Assets Carrying Value	543,139
Carrying Value, Secured borrowings	$ 403,644
Credit Suisse | Fixed rate, Transitional, Acquired loans | Borrowings under repurchase agreements | One Month LIBOR | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.00%
Credit Suisse | Fixed rate, Transitional, Acquired loans | Borrowings under repurchase agreements | One Month LIBOR | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.35%
Comerica Bank | Residential loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 100,000
Pledged Assets Carrying Value	69,194
Carrying Value, Secured borrowings	$ 63,991		78,312
Comerica Bank | Residential loans | Borrowings under credit facilities | One Month LIBOR
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	1.75%
TBK Bank | Residential loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 150,000
Pledged Assets Carrying Value	127,018
Carrying Value, Secured borrowings	125,145		123,951
Origin Bank | Residential loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	60,000
Pledged Assets Carrying Value	16,932
Carrying Value, Secured borrowings	16,052		27,450
Associated Bank | Residential loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	60,000
Pledged Assets Carrying Value	15,137
Carrying Value, Secured borrowings	$ 14,449		15,556
Associated Bank | Residential loans | Borrowings under credit facilities | One Month LIBOR
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	1.50%
Bank of the Sierra | Real estate | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 22,770
Carrying Value, Secured borrowings			22,611
Bank of the Sierra | Real estate | Borrowings under credit facilities | Minimum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	3.25%	3.25%
Bank of the Sierra | Real estate | Borrowings under credit facilities | Maximum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	3.45%	3.45%
Western Alliance | Residential loans | Borrowings under credit facilities
Secured borrowings and promissory note
Current facility size	$ 50,000
Pledged Assets Carrying Value	7,282
Carrying Value, Secured borrowings	6,823
Citibank | Fixed rate, Transitional, Acquired loans | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	500,000
Pledged Assets Carrying Value	165,547
Carrying Value, Secured borrowings	$ 128,851		210,735
Citibank | Fixed rate, Transitional, Acquired loans | Borrowings under repurchase agreements | One Month LIBOR | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.00%
Citibank | Fixed rate, Transitional, Acquired loans | Borrowings under repurchase agreements | One Month LIBOR | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	3.00%
Citibank | Mortgage backed securities | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 47,777
Pledged Assets Carrying Value	82,260
Carrying Value, Secured borrowings	$ 47,777		58,076
Citibank | Mortgage backed securities | Borrowings under repurchase agreements | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.32%
Pricing, stated rate (as a percent)	2.32%	2.32%
Deutsche Bank | Fixed rate, Transitional loans | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 350,000
Pledged Assets Carrying Value	309,295
Carrying Value, Secured borrowings	$ 236,073		190,567
Deutsche Bank | Fixed rate, Transitional loans | Borrowings under repurchase agreements | Secured Overnight Financing Rate | Minimum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	1.90%
Deutsche Bank | Fixed rate, Transitional loans | Borrowings under repurchase agreements | Secured Overnight Financing Rate | Maximum
Secured borrowings and promissory note
Pricing, spread on variable (as a percent)	2.75%
Deutsche Bank | Mortgage backed securities | Borrowings under repurchase agreements
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	2.37%	2.37%
Current facility size	$ 12,956
Pledged Assets Carrying Value	19,776
Carrying Value, Secured borrowings	12,956		16,354
RBC | Mortgage backed securities | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	61,302
Pledged Assets Carrying Value	90,012
Carrying Value, Secured borrowings	$ 61,302		$ 38,814
RBC | Mortgage backed securities | Borrowings under repurchase agreements | Minimum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	1.31%	1.31%
RBC | Mortgage backed securities | Borrowings under repurchase agreements | Maximum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	1.96%	1.96%
CSFB | Mortgage backed securities | Borrowings under repurchase agreements
Secured borrowings and promissory note
Current facility size	$ 95,467
Pledged Assets Carrying Value	132,658
Carrying Value, Secured borrowings	$ 95,467
CSFB | Mortgage backed securities | Borrowings under repurchase agreements | Minimum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	2.09%	2.09%
CSFB | Mortgage backed securities | Borrowings under repurchase agreements | Maximum
Secured borrowings and promissory note
Pricing, stated rate (as a percent)	2.95%	2.95%