Secured Debt Agreements - Revolving Repurchase Facilities (Detail) - Revolving Repurchase Facilities [Member]	Jun. 30, 2015 USD ($)
Line of Credit Facility [Line Items]
Maximum Facility Size	$ 4,146,798,000
Collateral Assets	3,910,571,000
Potential	3,049,212,000
Repurchase Borrowings Outstanding	2,636,822,000
Available	412,390,000
Wells Fargo [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	1,000,000,000
Collateral Assets	887,926,000
Potential	689,679,000
Repurchase Borrowings Outstanding	549,858,000
Available	139,821,000
JP Morgan [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	753,348,000
Collateral Assets	832,222,000
Potential	653,830,000
Repurchase Borrowings Outstanding	566,063,000
Available	87,767,000
Bank of America [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	750,000,000
Collateral Assets	815,125,000
Potential	642,169,000
Repurchase Borrowings Outstanding	606,535,000
Available	35,634,000
MetLife [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	750,000,000
Collateral Assets	556,409,000
Potential	433,445,000
Repurchase Borrowings Outstanding	364,153,000
Available	69,292,000
Citibank [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000
Collateral Assets	575,506,000
Potential	439,239,000
Repurchase Borrowings Outstanding	362,562,000
Available	76,677,000
Morgan Stanley [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	393,450,000
Collateral Assets	243,383,000
Potential	190,850,000
Repurchase Borrowings Outstanding	187,651,000
Available	$ 3,199,000

Repurchase Facility Maximum Borrowing Capacity

No definition available.

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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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.

+ References

No definition available.

+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the aggregate value of loans, trade receivables, securities and financial instruments that serve as collateral for obligations arising from a transfer of financial assets recorded as a secured borrowing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5086-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=55761124&loc=SL6224234-111729

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