Investment Securities - HTM (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
HTM Securities
Amortized Cost Basis		$ 493,462	$ 544,280
Credit Loss Allowance	$ (5,387)	(5,387)	(5,675)
Net Carrying Amount		488,075	538,605
Gross Unrealized Holdings Gains		3,781	847
Gross Unrealized Holdings Losses		(25,169)	(24,199)
Fair Value		466,687	515,253
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	5,675
Credit loss provision, net	(288)
Credit loss allowance at ending	5,387
HTM preferred equity interests
Less than one year		313,863
One to three years		139,261
Thereafter		34,951
Total		488,075	538,605
CMBS
HTM Securities
Amortized Cost Basis		339,120	339,059
Net Carrying Amount		339,120	339,059
Gross Unrealized Holdings Losses		(25,169)	(23,286)
Fair Value		313,951	315,773
HTM preferred equity interests
Less than one year		313,863
One to three years		25,257
Total		339,120	339,059
Preferred interests
HTM Securities
Amortized Cost Basis		116,466	166,614
Credit Loss Allowance	(2,462)	(2,462)	(2,749)
Net Carrying Amount		114,004	163,865
Gross Unrealized Holdings Gains		3,346	432
Gross Unrealized Holdings Losses			(913)
Fair Value		117,350	163,384
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	2,749
Credit loss provision, net	(287)
Credit loss allowance at ending	2,462
HTM preferred equity interests
One to three years		114,004
Total		114,004	163,865
Infrastructure bonds
HTM Securities
Amortized Cost Basis		37,876	38,607
Credit Loss Allowance	(2,925)	(2,925)	(2,926)
Net Carrying Amount		34,951	35,681
Gross Unrealized Holdings Gains		435	415
Fair Value		35,386	36,096
Activity in credit loss allowance for HTM debt securities
Credit loss allowance at beginning	2,926
Credit loss provision, net	(1)
Credit loss allowance at ending	$ 2,925
HTM preferred equity interests
Thereafter		34,951
Total		$ 34,951	$ 35,681