Commitments and Financial Instruments with Off-Balance-Sheet Risk (Details) (Standby letters of credit, USD $) In Millions, unless otherwise specified			9 Months Ended
Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Minimum	Sep. 30, 2013 Maximum
Commitments and Financial Instruments with Off-Balance-Sheet Risk
Standby letter of credit outstanding	$ 16.29	$ 17.29
Term of standby letter of credit			6 months	1 year

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