Guarantees (Narrative) (Details) (Financial Standby Letter of Credit [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Standby Letters of Credit Outstanding	$ 30.6	$ 28.2

The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

No definition available.

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