Financial Guarantees (Textual) (Details) - Financial Standby Letter of Credit [Member] - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Financial Guarantees (Textual) [Abstract]
Letters of credit outstanding	$ 45	$ 41	$ 37
Expiration period for letters of credit, maximum	5 years

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

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