Mortgage Loans on Real Estate - Schedule of Loans (UPB) Collateralized by Real Estate (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Residential Real Estate
Debt Instrument [Line Items]
Unpaid Principal Balance	[1],[2],[3]	$ 2,241,748	$ 1,851,539
Nonaccrual Unpaid Principal Balance	[3]	$ 266,367	$ 184,633
Residential Real Estate | Less Than One Million
Debt Instrument [Line Items]
Final Maturity Date	[3]	Jan. 01, 2054	Jan. 01, 2053
Unpaid Principal Balance	[1],[2],[3]	$ 1,674,434	$ 1,374,726
Nonaccrual Unpaid Principal Balance	[3]	$ 185,391	$ 127,125
Residential Real Estate | Less Than One Million | Minimum
Debt Instrument [Line Items]
Interest Rate	[3]	4.00%	4.00%
Residential Real Estate | Less Than One Million | Maximum
Debt Instrument [Line Items]
Interest Rate	[3]	14.00%	13.50%
Residential Real Estate | One Million And More
Debt Instrument [Line Items]
Final Maturity Date	[3]	Jan. 01, 2054	Jan. 01, 2053
Unpaid Principal Balance	[1],[2],[3]	$ 567,314	$ 476,813
Nonaccrual Unpaid Principal Balance	[3]	$ 80,976	$ 57,508
Residential Real Estate | One Million And More | Minimum
Debt Instrument [Line Items]
Interest Rate	[3]	4.00%	4.00%
Residential Real Estate | One Million And More | Maximum
Debt Instrument [Line Items]
Interest Rate	[3]	13.30%	11.50%
Commercial Real Estate
Debt Instrument [Line Items]
Unpaid Principal Balance	[1],[2],[4]	$ 1,831,142	$ 1,660,947
Nonaccrual Unpaid Principal Balance	[4]	$ 128,195	$ 108,156
Commercial Real Estate | Less Than One Million
Debt Instrument [Line Items]
Final Maturity Date	[4]	Jan. 01, 2054	Jan. 01, 2053
Unpaid Principal Balance	[1],[2],[4]	$ 1,322,387	$ 1,196,378
Nonaccrual Unpaid Principal Balance	[4]	$ 86,755	$ 69,763
Commercial Real Estate | Less Than One Million | Minimum
Debt Instrument [Line Items]
Interest Rate	[4]	4.00%	4.00%
Commercial Real Estate | Less Than One Million | Maximum
Debt Instrument [Line Items]
Interest Rate	[4]	15.00%	13.70%
Commercial Real Estate | One Million And More
Debt Instrument [Line Items]
Final Maturity Date	[4]	Jan. 01, 2054	Jan. 01, 2053
Unpaid Principal Balance	[1],[2],[4]	$ 508,755	$ 464,569
Nonaccrual Unpaid Principal Balance	[4]	$ 41,440	$ 38,393
Commercial Real Estate | One Million And More | Minimum
Debt Instrument [Line Items]
Interest Rate	[4]	4.00%	4.00%
Commercial Real Estate | One Million And More | Maximum
Debt Instrument [Line Items]
Interest Rate	[4]	13.20%	11.70%
Real Estate
Debt Instrument [Line Items]
Unpaid Principal Balance	[1],[2]	$ 4,072,890	$ 3,512,486
Nonaccrual Unpaid Principal Balance		$ 394,562	$ 292,789

[1] As of December 31, 2023 and 2022, $188.5 million and $168.4 million, respectively, of the total UPB were interest-only loans with interest payable monthly and the principal payable at maturity.

[2] The aggregate cost of the Company’s loan portfolio for Federal income tax purposes were $4,156,554 and $3,553,379 as of December 31, 2023 and 2022, respectively.

[3] The principal and interest on the 1-4 unit residential mortgage loans is payable monthly over the life of the loan to maturity. These loans generally contain a 3% prepayment penalty provision if the loan is prepaid within the first 3 years.

[4] The principal and interest on the traditional commercial mortgage loans is payable monthly over the life of the loan to maturity. These loans generally contain a 5% prepayment penalty provision if the loan is prepaid within the first 3 years.