Short-Term Borrowings (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Short Term Debt [Line Items]
Fair value of capital markets trading securities pledged to secure other short-term borrowings	80.1
Federal Funds Purchased And Securities Sold Under Agreements To Repurchase [Member]
Short Term Debt [Line Items]
Maximum maturity days	90 days
Trading Liabilities [Member]
Short Term Debt [Line Items]
Maximum holding days	90 days
Other Short Term Borrowings [Member]
Short Term Debt [Line Items]
Maximum original maturity period	1 year

The fair value of trading securities that serve as collateral for borrowings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph i

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5086-111524

Name:	us-gaap_TradingSecuritiesPledgedAsCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant