Contingencies, Guarantor (Details) (USD $)	Jun. 30, 2012 loans
Guarantor Obligations [Line Items]
Outstanding Student Loan Portfolio, Loans	4,000,000
Outstanding Principal Balance - Student Loan Portfolio	$ 57,900,000,000
Reserves for losses on defaulted loans	2,000,000
Contractual and Corporate Obligations Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum exposure, undiscounted	446,000,000
Surety Bonds Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum exposure, undiscounted	$ 769,000,000

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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