Trading Securities (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	$ 206,598,000	$ 214,102,000	$ 128,376,000
Trading Securities, Net Unrealized Gains (Losses)	239,000	151,000	217,000
US Government Agency Obligations [Member]
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	55,358,000	16,545,000	27,430,000
Trading Securities, Net Unrealized Gains (Losses)	48,000	(57,000)	2,000
U.S. Agency Residential Mortgage-backed Securities [Member]
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	33,106,000	86,361,000	35,111,000
Trading Securities, Net Unrealized Gains (Losses)	160,000	447,000	57,000
Municipal and Other Tax-exempt Securities [Member]
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	90,710,000	90,326,000	60,230,000
Trading Securities, Net Unrealized Gains (Losses)	(10,000)	(226,000)	158,000
Trading Securities, Pledged as Collateral		13,000,000
Other Trading Securities [Member]
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	27,424,000	20,870,000	5,605,000
Trading Securities, Net Unrealized Gains (Losses)	$ 41,000	$ (13,000)	$ 0

The total of financial instruments that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for debt and equity securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.4)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

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-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-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.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 29

-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 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Implementation Guide (Q and A)

-Number FAS115

-Paragraph 35

-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.

+ Details