Fair Value (Details 4) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Carrying amount and estimated fair value of financial instruments
Securities available for sale	$ 837,047		$ 691,000
Restricted Stock	21,050		21,292
FDIC Indemnification Asset	1,515	1,770	2,632	2,384
Accrued interest receivable	11,046		12,024
Deposits	(2,279,505)		(2,276,134)
Level 1
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	17,946		21,333
Federal funds sold	0		0
Securities available for sale	470		380
Restricted Stock	0		0
Loans, net	0		0
FDIC Indemnification Asset	0		0
Accrued interest receivable	0		0
Deposits	0		0
Short-term borrowings	0		0
Federal Home Loan Bank advances	0		0
Accrued interest payable	0		0
Level 2
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	55,774		65,897
Federal funds sold	10,215		20,800
Securities available for sale	821,899		674,587
Restricted Stock	0		0
Loans, net			0
FDIC Indemnification Asset	1,515		2,632
Accrued interest receivable	3,171		2,980
Deposits	(2,282,242)		(2,280,910)
Short-term borrowings	(29,194)		(40,551)
Federal Home Loan Bank advances	(211,786)		(124,933)
Accrued interest payable	(924)		(1,163)
Level 3
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	0		0
Federal funds sold	0		0
Securities available for sale	14,678		16,033
Restricted Stock	0		0
Loans, net	1,832,518		1,916,256
FDIC Indemnification Asset	0		0
Accrued interest receivable	7,875		9,044
Deposits	0		0
Short-term borrowings	0		0
Federal Home Loan Bank advances	0		0
Accrued interest payable	0		0
Carrying Value
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	73,720		87,230
Federal funds sold	10,215		20,800
Securities available for sale	837,047		691,000
Restricted Stock	21,050		21,292
Loans, net	1,777,186		1,829,978
FDIC Indemnification Asset	1,515		2,632
Accrued interest receivable	11,046		12,024
Deposits	(2,279,505)		(2,276,134)
Short-term borrowings	(29,194)		(40,551)
Federal Home Loan Bank advances	(209,534)		(119,705)
Accrued interest payable	(924)		(1,163)
Fair Value
Carrying amount and estimated fair value of financial instruments
Cash and due from banks	73,720		87,230
Federal funds sold	10,215		20,800
Securities available for sale	837,047		691,000
Restricted Stock	0		0
Loans, net	1,832,518		1,916,256
FDIC Indemnification Asset	1,515		2,632
Accrued interest receivable	11,046		12,024
Deposits	(2,282,242)		(2,280,910)
Short-term borrowings	(29,194)		(40,551)
Federal Home Loan Bank advances	(211,786)		(124,933)
Accrued interest payable	$ (924)		$ (1,163)

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

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-Section 50

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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Carrying amount of receivable assets originating from the indemnification agreement with the Federal Deposit Insurance Corporation (FDIC), in which the FDIC is to partially cover losses.

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Fair value portion of federal funds sold and securities borrowed or purchased under agreements to resell.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Amount of interest payable on debt, including, but not limited to, trade payables.

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-SubTopic 210

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-Section 03

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-Subparagraph a

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.

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