Investment Securities - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2025 USD ($) security preferred_interest shares	Mar. 31, 2024 USD ($)	Dec. 31, 2012 shares	Dec. 31, 2024 USD ($) security shares
Debt Securities, Available-for-sale [Line Items]
Cost of third party management	$ 200,000	$ 200,000
Number of securities with unrealized losses | security	13			13
Allowance for credit loss	$ 393,909,000			$ 431,424,000
HTM Preferred Intrests
Debt Securities, Available-for-sale [Line Items]
Unfunded commitments	$ 57,011,000
SEREF
Debt Securities, Available-for-sale [Line Items]
Number of shares acquired (in shares) | shares			9,140,000
Remaining held (in shares) | shares	3,420,384			4,480,649
Number of shares redeemed (in shares) | shares	1,060,265
Proceeds from shares redeemed	$ 1,400,000
Equity security, fair value	$ 3,800,000			$ 5,100,000
Ownership percentage	2.30%
Commercial loans: | HTM Preferred Intrests
Debt Securities, Available-for-sale [Line Items]
Unfunded commitments	$ 20,000,000.0
VIE eliminations
Debt Securities, Available-for-sale [Line Items]
Fair value of investment securities before consolidation of VIEs eliminated against VIE liabilities	31,300,000
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	$ 82,100,000
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	422,300,000
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	309,817,000			357,012,000
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	1,100,000,000
Unpaid principal balance of investment securities before consolidation of VIEs	2,700,000,000
Infrastructure bonds
Debt Securities, Available-for-sale [Line Items]
Allowance for credit loss	27,227,000			27,343,000
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	$ 56,865,000			$ 47,069,000
Preferred interests | Commercial loans:
Debt Securities, Available-for-sale [Line Items]
Number of commercial lending preferred interests | preferred_interest	6
Debt securities, held-to-maturity, nonaccrual	$ 39,100,000
Amortized cost of interest placed on nonaccrual during period	$ 3,500,000