Loans and Investments - Risk Ratings and LTV Ratios (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Loans and Investments
Loans and investments, gross	$ 12,615,006	$ 14,456,123
Percentage of Portfolio	100.00%	100.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	1.00%	1.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	78.00%	76.00%
Charge-offs, 2023	$ 0
Charge-offs, 2022	0
Charge-offs, 2021	0
Charge-offs, 2020	0
Charge-offs, 2019	0
Charge-offs, Prior	5,700
Charge-offs, Total	5,700
Credit Risk Concentration
Loans and Investments
Origination Year 2023	752,918
Origination Year 2022	5,324,481
Origination year 2021	5,581,489
Origination Year 2020	488,628
Origination Year 2019	239,648
Origination Year Prior	227,842
Loans and investments, gross	$ 12,615,006
Wtd. Avg. First Dollar LTV Ratio (as percent)	1.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	78.00%
Multifamily \| Credit Risk Concentration
Loans and Investments
Origination Year 2023	$ 422,596
Origination Year 2022	4,813,671
Origination year 2021	5,217,946
Origination Year 2020	325,426
Origination Year 2019	239,648
Origination Year Prior	78,694
Loans and investments, gross	$ 11,097,981
Percentage of Portfolio	88.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	1.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	80.00%
Multifamily \| Credit Risk Concentration \| Pass
Loans and Investments
Origination Year 2023	$ 80,814
Origination Year 2022	53,316
Origination year 2021	26,185
Origination Year 2020	2,010
Origination Year 2019	4,598
Origination Year Prior	20,300
Loans and investments, gross	187,223
Multifamily \| Credit Risk Concentration \| Pass/Watch
Loans and Investments
Origination Year 2023	317,358
Origination Year 2022	2,561,938
Origination year 2021	2,223,155
Origination Year 2020	119,860
Origination Year 2019	84,600
Origination Year Prior	58,044
Loans and investments, gross	5,364,955
Multifamily \| Credit Risk Concentration \| Special Mention
Loans and Investments
Origination Year 2023	24,424
Origination Year 2022	1,762,539
Origination year 2021	2,631,689
Origination Year 2020	180,750
Origination Year 2019	140,685
Origination Year Prior	350
Loans and investments, gross	4,740,437
Multifamily \| Credit Risk Concentration \| Substandard
Loans and Investments
Origination Year 2023	0
Origination Year 2022	435,878
Origination year 2021	322,987
Origination Year 2020	8,006
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	766,871
Multifamily \| Credit Risk Concentration \| Doubtful
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	13,930
Origination Year 2020	14,800
Origination Year 2019	9,765
Origination Year Prior	0
Loans and investments, gross	38,495
Single- Family Rental \| Credit Risk Concentration
Loans and Investments
Origination Year 2023	330,322
Origination Year 2022	510,810
Origination year 2021	363,543
Origination Year 2020	119,692
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	$ 1,324,367
Percentage of Portfolio	10.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	0.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	62.00%
Single- Family Rental \| Credit Risk Concentration \| Pass
Loans and Investments
Origination Year 2023	$ 9,709
Origination Year 2022	608
Origination year 2021	0
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	10,317
Single- Family Rental \| Credit Risk Concentration \| Pass/Watch
Loans and Investments
Origination Year 2023	289,482
Origination Year 2022	465,057
Origination year 2021	144,846
Origination Year 2020	119,692
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	1,019,077
Single- Family Rental \| Credit Risk Concentration \| Special Mention
Loans and Investments
Origination Year 2023	31,131
Origination Year 2022	45,145
Origination year 2021	218,697
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	294,973
Land \| Credit Risk Concentration
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	8,100
Origination Year 2019	0
Origination Year Prior	127,928
Loans and investments, gross	$ 136,028
Percentage of Portfolio	1.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	0.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	97.00%
Land \| Credit Risk Concentration \| Pass/Watch
Loans and Investments
Origination Year 2023	$ 0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	4,600
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	4,600
Land \| Credit Risk Concentration \| Special Mention
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	3,500
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	3,500
Land \| Credit Risk Concentration \| Substandard
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	127,928
Loans and investments, gross	127,928
Office \| Credit Risk Concentration
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	35,410
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	$ 35,410
Percentage of Portfolio	1.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	0.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	80.00%
Office \| Credit Risk Concentration \| Special Mention
Loans and Investments
Origination Year 2023	$ 0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	35,410
Origination Year 2019	0
Origination Year Prior	0
Loans and investments, gross	35,410
Retail \| Credit Risk Concentration
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	19,520
Loans and investments, gross	$ 19,520
Percentage of Portfolio	1.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	0.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	88.00%
Retail \| Credit Risk Concentration \| Substandard
Loans and Investments
Origination Year 2023	$ 0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	19,520
Loans and investments, gross	19,520
Commercial \| Credit Risk Concentration
Loans and Investments
Origination Year 2023	0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	1,700
Loans and investments, gross	$ 1,700
Percentage of Portfolio	1.00%
Wtd. Avg. First Dollar LTV Ratio (as percent)	63.00%
Wtd. Avg. Last Dollar LTV Ratio (as percent)	66.00%
Commercial \| Credit Risk Concentration \| Doubtful
Loans and Investments
Origination Year 2023	$ 0
Origination Year 2022	0
Origination year 2021	0
Origination Year 2020	0
Origination Year 2019	0
Origination Year Prior	1,700
Loans and investments, gross	$ 1,700

Represents the weighted average First Dollar LTV Ratio that is calculated by comparing the total of the company's senior most dollar and all senior lien positions within the capital stack to the fair value of the underlying collateral to determine the point at which the company will absorb a total loss of its position.

No definition available.