Subordinated Debentures Held by Subsidiary Trusts - Financial Insruments Subject to Mandatory Redemption (Details) (Trusts, USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Trust Preferred Securities Subject to Mandatory Redemption
Financial Instruments Subject to Mandatory Redemption by Settlement Terms
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount	$ 120,000
Common Stock Subject to Mandatory Redemption
Financial Instruments Subject to Mandatory Redemption by Settlement Terms
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount	$ 3,715

No authoritative reference available.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6940734&loc=d3e22047-110879

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 150

-Paragraph 27

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant