Notes Receivable - Principal Payments (Net of Reserves and Unamortized Discounts) and Interest Rates (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
2015	$ 20
2016	73
2017	3
2018	4
2019	2
Thereafter	143
Senior, mezzanine, and other loans	$ 245us-gaap_NotesReceivableNet	$ 242us-gaap_NotesReceivableNet
Weighted average interest rate at March 31, 2015	6.00%
Range of stated interest rates at March 31, 2015, minimum	0.00%
Range of stated interest rates at March 31, 2015. maximum	9.00%

Notes Receivable, Future Principal Payments Receivable, After Year Five

No definition available.

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- Definition

Notes Receivable, Future Principal Payments Receivable, Current

+ References

No definition available.

+ Details

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- Definition

Notes Receivable, Future Principal Payments Receivable, in Five Years

+ References

No definition available.

+ Details

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- Definition

Notes Receivable, Future Principal Payments Receivable, in Four Years

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Notes Receivable, Future Principal Payments Receivable, in Three Years

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Notes Receivable, Future Principal Payments Receivable, in Two Years

+ References

No definition available.

+ Details

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- Definition

Upper limit of range of stated interest rates for total notes receivable as of the balance sheet date indicated.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Lower limit of range of stated interest rates for total notes receivable as of the balance sheet date indicated.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Weighted average interest rate for total notes receivable as of the balance sheet date indicated.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ 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 210.5-02.3)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Article 5

+ Details

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- Details

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