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Residential Mortgage Securities and MSR-Related Assets (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Minimum term of fixed rate mortgages underlying MBS	15 years
Maximum term of fixed rate mortgages underlying MBS	30 years
Impairment and other losses on securities available-for-sale and other assets	$ 419,651,000	$ 0
Available-for-sale, unrealized loss position, accumulated loss	89,388,000
Loans in Unrealized Loss Position
Debt Securities, Available-for-sale [Line Items]
Impairment and other losses on securities available-for-sale and other assets	(63,500,000)
Agency MBS
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, unrealized loss position, accumulated loss	0
Non-Agency MBS
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, unrealized loss position, accumulated loss	$ 21,643,000
Minimum | RPL/NPL MBS
Debt Securities, Available-for-sale [Line Items]
Debt instrument, basis spread on variable rate	3.00%
Debt instrument, coupon step-up period	36 months
Maximum | RPL/NPL MBS
Debt Securities, Available-for-sale [Line Items]
Debt instrument, basis spread on variable rate	4.00%
Debt instrument, coupon step-up period	48 months

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- Definition

Debt Instrument, Coupon Step-Up Period

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- Definition

Impairment and Other Losses On Securities Available-for-Sale And Other Assets

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- Definition

Represents the minimum period of the fixed rate mortgages which act as security for mortgage backed securities in the entity's portfolio.

+ References

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- Definition

Mortgage Backed Securities, Period of Fixed Rate Mortgages Maximum

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922888-210455

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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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