Financial Guarantees (Textual) (Details) - Financial Standby Letter of Credit [Member] - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Financial Guarantees (Textual) [Abstract]
Letters of credit outstanding	$ 43	$ 39	$ 38
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