Contingencies and Litigation - Guarantor (Details) (USD $)	Dec. 31, 2013 loans
Guarantor Obligations [Line Items]
Outstanding student loan portfolio, loans	3,200,000
Outstanding principal balance - student loan portfolio	$ 45,800,000,000
Reserves for losses on defaulted loans	3,000,000
Other contingencies letter of credits [Member]
Guarantor Obligations [Line Items]
Maximum exposure, undiscounted	457,000,000
Surety bonds guarantee [Member]
Guarantor Obligations [Line Items]
Maximum exposure, undiscounted	$ 736,000,000

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 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

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