Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	$ 644,715	$ 637,940
Gross Unrealized Gains, Securities Available for Sale	7,145	7,011
Gross Unrealized Losses, Securities Available for Sale	(2,664)	(1,901)
Fair Value, Securities Available for Sale	649,196	643,050
Gross Amortized Cost, Securities Held for Investment		13,818
Gross Unrealized Gains, Securities Held for Investment		819
Gross Unrealized Losses, Securities Held for Investment		(95)
Fair value, Securities Held for Investment		14,542
U.S. Treasury securities and obligations of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	1,200	1,700
Gross Unrealized Gains, Securities Available for Sale	2	7
Gross Unrealized Losses, Securities Available for Sale	0	0
Fair Value, Securities Available for Sale	1,202	1,707
Mortgage-backed securities of U.S Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	175,283	186,404
Gross Unrealized Gains, Securities Available for Sale	3,022	3,320
Gross Unrealized Losses, Securities Available for Sale	(904)	(469)
Fair Value, Securities Available for Sale	177,401	189,255
Collateralized mortgage obligations of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	366,890	352,731
Gross Unrealized Gains, Securities Available for Sale	2,201	2,430
Gross Unrealized Losses, Securities Available for Sale	(1,219)	(902)
Fair Value, Securities Available for Sale	367,872	354,259
Gross Amortized Cost, Securities Held for Investment		4,687
Gross Unrealized Gains, Securities Held for Investment		0
Gross Unrealized Losses, Securities Held for Investment		(92)
Fair value, Securities Held for Investment		4,595
Private collateralized mortgage obligations [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	92,643	96,258
Gross Unrealized Gains, Securities Available for Sale	1,194	1,203
Gross Unrealized Losses, Securities Available for Sale	(539)	(530)
Fair Value, Securities Available for Sale	93,298	96,931
Gross Amortized Cost, Securities Held for Investment		1,278
Gross Unrealized Gains, Securities Held for Investment		33
Gross Unrealized Losses, Securities Held for Investment		0
Fair value, Securities Held for Investment		1,311
Obligations of state and political subdivisions [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	7,199	847
Gross Unrealized Gains, Securities Available for Sale	688	51
Gross Unrealized Losses, Securities Available for Sale	(2)	0
Fair Value, Securities Available for Sale	7,885	898
Gross Amortized Cost, Securities Held for Investment		6,353
Gross Unrealized Gains, Securities Held for Investment		737
Gross Unrealized Losses, Securities Held for Investment		(3)
Fair value, Securities Held for Investment		7,087
Other [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	1,500
Gross Unrealized Gains, Securities Available for Sale	38
Gross Unrealized Losses, Securities Available for Sale	0
Fair Value, Securities Available for Sale	1,538
Gross Amortized Cost, Securities Held for Investment		1,500
Gross Unrealized Gains, Securities Held for Investment		49
Gross Unrealized Losses, Securities Held for Investment		0
Fair value, Securities Held for Investment		$ 1,549

Amount of debt securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

-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 Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 137

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-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

-Topic 942

-SubTopic 320

-Section 50

-Paragraph 2

-Subparagraph (b)-(g)

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-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 9: 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 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-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

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details

- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

+ References+ Details

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

+ References+ Details