Financial Instruments - Narrative (Details)	12 Months Ended
Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Illiquidity discount	10.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Time period between issuance of loan commitment and closing and sale of loan	60 days

Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration