Amount of assets pledged to secure a debt instrument.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Name Accounting Standards Codification
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-Section S99
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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.

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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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No definition available.

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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.

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

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Secured Debt Agreements, Net - Credit Facilities (Detail)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 GBP (£)	Sep. 30, 2017 EUR (€)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 GBP (£)	Dec. 31, 2016 EUR (€)
Line of Credit Facility [Line Items]
Potential	$ 4,989,350,000
Repurchase Borrowings Outstanding	4,386,645,000
Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	7,137,810,000			$ 5,479,180,000
Collateral Assets	6,424,646,000			5,297,728,000
Potential	4,989,350,000			4,114,580,000
Repurchase Borrowings Outstanding	4,386,645,000			3,572,837,000
Available	602,705,000			541,743,000
Wells Fargo [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	2,000,000,000			2,000,000,000
Collateral Assets	2,232,117,000			1,718,874,000
Potential	1,724,227,000			1,339,942,000
Repurchase Borrowings Outstanding	1,398,224,000			1,107,733,000
Available	326,003,000			232,209,000
MetLife [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	1,000,000,000			1,000,000,000
Collateral Assets	1,030,148,000			1,106,017,000
Potential	807,164,000			862,454,000
Repurchase Borrowings Outstanding	807,164,000			862,454,000
Bank of America [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	750,000,000			750,000,000
Collateral Assets	818,359,000			794,881,000
Potential	641,066,000			617,694,000
Repurchase Borrowings Outstanding	641,066,000			617,694,000
Societe Generale [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	472,560,000		€ 400,000,000	420,680,000		€ 400,000,000
Collateral Assets	332,761,000			274,351,000
Potential	266,000,000			207,178,000
Repurchase Borrowings Outstanding	266,000,000			207,178,000
Deutsche Bank [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000
Collateral Assets	393,564,000
Potential	295,743,000
Repurchase Borrowings Outstanding	295,743,000
Citibank [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	795,350,000			500,000,000
Collateral Assets	596,119,000			508,989,000
Potential	464,849,000			394,677,000
Repurchase Borrowings Outstanding	356,751,000			229,629,000
Available	108,098,000			165,048,000
Morgan Stanley [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	669,900,000	£ 500,000,000		308,500,000	£ 250,000,000
Collateral Assets	422,332,000			344,056,000
Potential	331,037,000			272,221,000
Repurchase Borrowings Outstanding	211,105,000			231,930,000
Available	119,932,000			40,291,000
JP Morgan [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000			500,000,000
Collateral Assets	453,121,000			550,560,000
Potential	344,656,000			420,414,000
Repurchase Borrowings Outstanding	295,984,000			316,219,000
Available	48,672,000			$ 104,195,000
Bank of America - Multi. JV [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	200,000,000
Collateral Assets	87,000,000
Potential	69,600,000
Repurchase Borrowings Outstanding	69,600,000
Goldman Sachs - Multi. JV [Member] \| Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	250,000,000
Collateral Assets	59,125,000
Potential	45,008,000
Repurchase Borrowings Outstanding	$ 45,008,000