Investment Securities - HTM (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
HTM Securities
Net Carrying Amount (Amortized Cost)	$ 592,163	$ 644,149
Gross Unrealized Holdings Gains	2,834	3,316
Gross Unrealized Holdings Losses	(1,224)	(3,517)
Fair Value	593,773	643,948
HTM preferred equity interests
Less than one year	75,204
One to three years	295,538
Three to five years	175,183
Thereafter	46,238
Total	592,163	644,149
CMBS
HTM Securities
Net Carrying Amount (Amortized Cost)	361,648	408,556
Gross Unrealized Holdings Gains	1,534	2,435
Gross Unrealized Holdings Losses	(649)	(3,349)
Fair Value	362,533	407,642
HTM preferred equity interests
Less than one year	75,204
One to three years	286,444
Total	361,648	408,556
Preferred interests
HTM Securities
Net Carrying Amount (Amortized Cost)	175,183	174,825
Gross Unrealized Holdings Gains	583	703
Fair Value	175,766	175,528
HTM preferred equity interests
Three to five years	175,183
Total	175,183	174,825
Infrastructure bonds
HTM Securities
Net Carrying Amount (Amortized Cost)	55,332	60,768
Gross Unrealized Holdings Gains	717	178
Gross Unrealized Holdings Losses	(575)	(168)
Fair Value	55,474	60,778
HTM preferred equity interests
One to three years	9,094
Thereafter	46,238
Total	$ 55,332	$ 60,768