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Investment Securities - Narrative (Details)	3 Months Ended		12 Months Ended
Investment Securities - Narrative (Details)	Mar. 31, 2026 USD ($) security preferred_interest shares	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) security preferred_interest shares	Dec. 31, 2012 shares
Debt Securities, Available-for-sale [Line Items]
Cost of third party management	$ 100,000	$ 200,000
Number of securities with unrealized losses \| security	17		14
Allowance for credit loss	$ 229,632,000		$ 216,936,000
Equity security, fair value			$ 628,000
SEREF
Debt Securities, Available-for-sale [Line Items]
Number of shares acquired (in shares) \| shares				9,140,000
Remaining held (in shares) \| shares			536,129
Equity security, fair value			$ 600,000
Number of shares redeemed (in shares) \| shares	536,129
Proceeds from shares redeemed	$ 600,000
VIE eliminations
Debt Securities, Available-for-sale [Line Items]
Fair value of investment securities before consolidation of VIEs eliminated against VIE liabilities	38,800,000
Fair Value Option
Debt Securities, Available-for-sale [Line Items]
Fair value of mortgage backed securities	1,600,000,000
RMBS
Debt Securities, Available-for-sale [Line Items]
Portion of securities with variable rate	$ 77,100,000
RMBS \| Available-for-sale
Debt Securities, Available-for-sale [Line Items]
Portion of securities with variable rate (as a percent)	89.00%
RMBS \| Fair Value Option
Debt Securities, Available-for-sale [Line Items]
Portion of securities with variable rate	$ 0
Fair value of investment securities before consolidation of VIEs	400,300,000
Unpaid principal balance of investment securities before consolidation of VIEs	326,300,000
CMBS
Debt Securities, Available-for-sale [Line Items]
Allowance for credit loss	90,130,000		92,629,000
CMBS \| Fair Value Option
Debt Securities, Available-for-sale [Line Items]
Portion of securities with variable rate	0
Fair value of investment securities before consolidation of VIEs	1,200,000,000
Unpaid principal balance of investment securities before consolidation of VIEs	2,800,000,000
Infrastructure bonds
Debt Securities, Available-for-sale [Line Items]
Allowance for credit loss	40,461,000		41,463,000
Infrastructure bonds \| Choctaw, Mississippi \| Infrastructure loans: \| Credit deteriorated
Debt Securities, Available-for-sale [Line Items]
Allowance for credit loss to date	10,000,000.0		10,000,000.0
Allowance for credit loss	19,200,000		19,200,000
Preferred interests
Debt Securities, Available-for-sale [Line Items]
Allowance for credit loss	$ 99,041,000		$ 82,844,000
Preferred interests \| Commercial loans:
Debt Securities, Available-for-sale [Line Items]
Number of commercial lending preferred interests \| preferred_interest	7		7
Debt securities, held-to-maturity, nonaccrual	$ 81,200,000		$ 65,000,000.0
Unfunded commitments	$ 60,200,000		$ 76,400,000