Fair Value - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financial assets:
Loans and investments, net - Principal/Notional Amount	$ 12,615,006	$ 14,456,123
Loans and investments, net	12,377,806	14,254,674	$ 11,981,048	$ 5,285,868
Loans held-for-sale, net - Principal/Notional Amount	552,325	368,066
Loans held-for-sale, net	552,325	368,066
Securities, held-to-maturity, net - Principal/Notional Amount	230,495	234,255
Securities held-to-maturity, net	155,279	156,547
Derivative financial instruments - Principal/Notional Amount	$ 447,609	$ 111,950
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Financial liabilities:
Credit and repurchase facilities, principal/notional amount	$ 3,242,939	$ 3,856,009
Credit and repurchase facilities	3,237,827	3,841,814
Securitized debt	6,935,010	7,849,270
Senior unsecured notes	1,333,968	1,385,994
Convertible senior unsecured notes, net	283,118	280,356
Junior subordinated notes	143,896	143,128
Derivative financial instruments - Principal/Notional Amount	$ 138,270	$ 273,973
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities	Other liabilities
Minimum
Financial liabilities:
Period of loans held for sale sold	60 days
Maximum
Financial liabilities:
Period of loans held for sale sold	180 days
Carrying Value
Financial assets:
Loans and investments, net	$ 12,377,806	$ 14,254,674
Loans held-for-sale, net	551,707	354,070
Capitalized mortgage servicing rights, net	391,254	401,471
Securities held-to-maturity, net	155,279	156,547
Derivative financial instruments	6,547	1,505
Financial liabilities:
Credit and repurchase facilities	3,237,827	3,841,814
Securitized debt	6,935,010	7,849,270
Senior unsecured notes	1,333,968	1,385,994
Convertible senior unsecured notes, net	283,118	280,356
Junior subordinated notes	143,896	143,128
Derivative financial instruments	1,021	4,897
Estimated Fair Value
Financial assets:
Loans and investments, net	12,452,563	14,468,418
Loans held-for-sale, net	566,451	362,054
Capitalized mortgage servicing rights, net	510,472	530,913
Securities held-to-maturity, net	129,390	144,571
Derivative financial instruments	6,547	1,505
Financial liabilities:
Credit and repurchase facilities	3,228,324	3,828,192
Securitized debt	6,864,557	7,560,541
Senior unsecured notes	1,214,331	1,262,560
Convertible senior unsecured notes, net	301,156	287,834
Junior subordinated notes	106,444	103,977
Derivative financial instruments	1,021	4,897
Securitized debt
Financial liabilities:
Debt face value issued to third parties	6,956,284	7,886,066
Senior unsecured notes
Financial liabilities:
Debt face value issued to third parties	1,345,000	1,399,600
Convertible senior unsecured notes, net
Financial liabilities:
Debt face value issued to third parties	287,500	287,500
Junior subordinated notes
Financial liabilities:
Debt face value issued to third parties	154,336	154,336
Junior subordinated notes	$ 143,900	$ 143,100