Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	$ 580,813	$ 639,847
Gross Unrealized Gains, Available for Sale	8,634	12,355
Gross Unrealized Losses, Available for Sale	(1,199)	(3,840)
Fair Value, Available for Sale	588,248	648,362
Gross Amortized Cost, Held for Investment Securities	15,556	19,977
Gross Unrealized Gains, Held for Investment Securities	891	646
Gross Unrealized Losses, Held for Investment Securities	(113)	(136)
Fair value, Held for Investment Securities	16,334	20,487
US Treasury securities and obligations of US Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	1,700	1,699
Gross Unrealized Gains, Available for Sale	11	25
Gross Unrealized Losses, Available for Sale	0	0
Fair Value, Available for Sale	1,711	1,724
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, Available for Sale	169,569	135,665
Gross Unrealized Gains, Available for Sale	4,057	2,819
Gross Unrealized Losses, Available for Sale	(86)	(37)
Fair Value, Available for Sale	173,540	138,447
Gross Amortized Cost, Held for Investment Securities	0
Fair value, Held for Investment Securities	0
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, Available for Sale	315,420	428,139
Gross Unrealized Gains, Available for Sale	2,496	9,111
Gross Unrealized Losses, Available for Sale	(1,029)	(316)
Fair Value, Available for Sale	316,887	436,934
Gross Amortized Cost, Held for Investment Securities	5,991	10,475
Gross Unrealized Gains, Held for Investment Securities	0	0
Gross Unrealized Losses, Held for Investment Securities	(105)	(136)
Fair value, Held for Investment Securities	5,886	10,339
Private collateralized mortgage obligations [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	93,277	73,247
Gross Unrealized Gains, Available for Sale	2,012	330
Gross Unrealized Losses, Available for Sale	(84)	(3,487)
Fair Value, Available for Sale	95,205	70,090
Gross Amortized Cost, Held for Investment Securities	1,406	1,840
Gross Unrealized Gains, Held for Investment Securities	37	40
Gross Unrealized Losses, Held for Investment Securities	0	0
Fair value, Held for Investment Securities	1,443	1,880
Obligations of state and political subdivisions [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	847	1,097
Gross Unrealized Gains, Available for Sale	58	70
Gross Unrealized Losses, Available for Sale	0	0
Fair Value, Available for Sale	905	1,167
Gross Amortized Cost, Held for Investment Securities	6,659	6,662
Gross Unrealized Gains, Held for Investment Securities	787	570
Gross Unrealized Losses, Held for Investment Securities	(8)	0
Fair value, Held for Investment Securities	7,438	7,232
Other [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Held for Investment Securities	1,500	1,000
Gross Unrealized Gains, Held for Investment Securities	67	36
Gross Unrealized Losses, Held for Investment Securities	0	0
Fair value, Held for Investment Securities	$ 1,567	$ 1,036

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

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

-Publisher FASB

-Name Accounting Standards Codification

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

-Publisher FASB

-Name Accounting Standards Codification

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

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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