Investment Securities - HTM Debt Securities, Amortized Cost​ (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
HTM Securities
Amortized Cost Basis	$ 604,942	$ 676,652
Credit Loss Allowance	(12,994)	(3,182)
Net Carrying Amount	591,948	673,470
Gross Unrealized Holding Gains	237	202
Gross Unrealized Holding Losses	(29,662)	(36,397)
Fair Value	562,523	637,275
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	3,182
Credit loss provision, net	9,812
Credit loss allowance at ending	12,994
HTM preferred equity interests
Less than one year	96,520
One to three years	432,007
Three to five years	54,307
Thereafter	9,114
Total	591,948
CMBS
HTM Securities
Amortized Cost Basis	569,867	577,681
Credit Loss Allowance	(492)	(172)
Net Carrying Amount	569,375	577,509
Gross Unrealized Holding Gains	79	30
Gross Unrealized Holding Losses	(28,474)	(30,424)
Fair Value	540,980	547,115
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	172
Credit loss provision, net	320
Credit loss allowance at ending	492
HTM preferred equity interests
Less than one year	96,520
One to three years	428,684
Three to five years	44,171
Thereafter	0
Total	569,375
Preferred interests
HTM Securities
Amortized Cost Basis	5,411	29,757
Credit Loss Allowance	(2,420)	0
Net Carrying Amount	2,991	29,757
Gross Unrealized Holding Gains	125	125
Gross Unrealized Holding Losses	(1,170)	(4,863)
Fair Value	1,946	25,019
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	0
Credit loss provision, net	2,420
Credit loss allowance at ending	2,420
HTM preferred equity interests
Less than one year	0
One to three years	2,991
Three to five years	0
Thereafter	0
Total	2,991
Infrastructure bonds
HTM Securities
Amortized Cost Basis	29,664	69,214
Credit Loss Allowance	(10,082)	(3,010)
Net Carrying Amount	19,582	66,204
Gross Unrealized Holding Gains	33	47
Gross Unrealized Holding Losses	(18)	(1,110)
Fair Value	19,597	$ 65,141
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	3,010
Credit loss provision, net	7,072
Credit loss allowance at ending	10,082
HTM preferred equity interests
Less than one year	0
One to three years	332
Three to five years	10,136
Thereafter	9,114
Total	$ 19,582