Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

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- Definition

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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- Definition

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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Derivative Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Gain (loss) on derivatives	$ (53,543)	$ 9,930	$ (80,832)	$ 23,342
Interest rate swap agreements
Derivative [Line Items]
Derivative contract, weighted average maturity (in months)			43 months
Aggregate notional amount	$ 2,956,000		$ 2,956,000		$ 3,306,000
Interest rate swap agreements \| Minimum
Derivative [Line Items]
Fixed interest rate	1.287%		1.287%
Interest rate swap agreements \| Maximum
Derivative [Line Items]
Fixed interest rate	3.2205%		3.2205%
TBA Agency MBS
Derivative [Line Items]
Gain (loss) on derivatives	$ 4,167	$ (3,926)	$ 10,596	$ (15,907)
Aggregate notional amount	$ 730,000		$ 730,000
TBA Agency MBS \| Minimum
Derivative [Line Items]
Fixed interest rate	3.50%		3.50%
TBA Agency MBS \| Maximum
Derivative [Line Items]
Fixed interest rate	4.00%		4.00%