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Investment Securities Available For Sale - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Proceeds from sale of investment securities, available-for-sale	$ 98,000,000.0	$ 26,900,000	$ 107,100,000
Net realized gain (loss) on investment securities available for sale	$ 21,800,000	$ (12,300,000)	(100,000)
Contractual maturities (up to)	40 years
Available for sale securities portfolio, weighted average life	5 years	5 years 8 months 12 days
Gross unrealized losses	$ (7,591,000)	$ (40,126,000)
Other-than-temporary Impairment loss	0	0	$ 0
Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(7,454,000)	(38,284,000)
Non-Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(13,000.0)	(1,466,000)
CMBS
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	$ (124,000)	$ (376,000)

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Represents the weighted average life of the available for sale securities portfolio.

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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

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Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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