Investment Securities Available For Sale - Unrealized Losses in OCI (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Carrying Value	$ 25,507,000	$ 573,470,000
Less than 12 Months, Gross Unrealized Losses	124,000	9,864,000
Greater than 12 Months, Carrying Value	222,390,000	726,186,000
Greater than 12 months, Gross Unrealized Losses	7,467,000	30,262,000
Total, Carrying Value	247,897,000	1,299,656,000
Total, Gross Unrealized Losses	7,591,000	40,126,000
Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Carrying Value	0	310,783,000
Less than 12 Months, Gross Unrealized Losses	0	8,037,000
Greater than 12 Months, Carrying Value	222,286,000	726,028,000
Greater than 12 months, Gross Unrealized Losses	7,454,000	30,247,000
Total, Carrying Value	222,286,000	1,036,811,000
Total, Gross Unrealized Losses	7,454,000	38,284,000
Non-Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Carrying Value	0	187,395,000
Less than 12 Months, Gross Unrealized Losses	0	1,451,000
Greater than 12 Months, Carrying Value	104,000	158,000
Greater than 12 months, Gross Unrealized Losses	13,000	15,000
Total, Carrying Value	104,000	187,553,000
Total, Gross Unrealized Losses	13,000.0	1,466,000
CMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Carrying Value	25,507,000	75,292,000
Less than 12 Months, Gross Unrealized Losses	124,000	376,000
Greater than 12 Months, Carrying Value	0	0
Greater than 12 months, Gross Unrealized Losses	0	0
Total, Carrying Value	25,507,000	75,292,000
Total, Gross Unrealized Losses	$ 124,000	$ 376,000

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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