Fair Values and Related Carrying Amounts of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 89,362		$ 128,208		$ 61,776	$ 96,467
Interest-bearing deposits with financial institutions	2,423		2,423
Federal Reserve Bank and Federal Home Loan Bank Stock	8,918		10,284
Securities available for sale, at fair value	69,950		86,378
Loans held for sale	10,672		55,809
Loans, net	717,818		719,257
Other assets - Mortgage servicing rights	3,823		2,801
Derivative assets - IRLC's	81		580
Derivative assets - TBA securities	540
Total assets measured at fair value on a recurring basis	85,066		145,568
Noninterest bearing deposits	(188,149)		(170,259)
Interest-bearing deposits	(560,831)		(675,136)
Borrowings	(45,000)		(55,000)
Junior subordinated debentures	(17,527)		(17,527)
Derivative liabilities - TBA securities			(158)
Total liabilities measured at fair value on a recurring basis			(158)
Mortgage backed securities issued by U.S. Agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	62,634	[1]	78,446	[1]
Collateralized Mortgage Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	2,308		2,625
Asset backed security
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	775	[2]	900	[2]
Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	4,233	[3]	4,407	[3]
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	4,233		4,407
Total assets measured at fair value on a recurring basis	4,233		4,407
Level 1 | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	4,233		4,407
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	64,942		80,409
Loans held for sale	10,672		55,809
Total assets measured at fair value on a recurring basis	75,614		136,218
Derivative liabilities - TBA securities			(158)
Total liabilities measured at fair value on a recurring basis			(158)
Level 2 | Mortgage backed securities issued by U.S. Agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	62,634		78,446
Level 2 | Collateralized Mortgage Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	2,308		1,963
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	775		1,562
Other assets - Mortgage servicing rights	3,823		2,801
Derivative assets - IRLC's	81		580
Derivative assets - TBA securities	540
Total assets measured at fair value on a recurring basis	5,219		4,943
Level 3 | Collateralized Mortgage Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value			662
Level 3 | Asset backed security
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	775		900
Derivative Financial Instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	89,362		128,208
Interest-bearing deposits with financial institutions	2,423		2,423
Federal Reserve Bank and Federal Home Loan Bank Stock	8,918		10,284
Loans held for sale	10,672		55,809
Loans, net	717,818		719,257
Other assets - Mortgage servicing rights	3,823		2,801
Derivative assets - IRLC's	81		580
Derivative assets - TBA securities	540
Total assets measured at fair value on a recurring basis	903,587		1,005,740
Noninterest bearing deposits	(188,149)		(170,259)
Interest-bearing deposits	(560,831)		(675,136)
Borrowings	(45,000)		(45,000)
Junior subordinated debentures	(17,527)		(17,527)
Derivative liabilities - TBA securities			(158)
Total liabilities measured at fair value on a recurring basis	(811,507)		(908,080)
Derivative Financial Instruments | Mortgage backed securities issued by U.S. Agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	62,634		78,446
Derivative Financial Instruments | Collateralized Mortgage Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	2,308		2,625
Derivative Financial Instruments | Asset backed security
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	775		900
Derivative Financial Instruments | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	4,233		4,407
Derivative Financial Instruments | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	89,362		128,208
Interest-bearing deposits with financial institutions	2,423		2,423
Federal Reserve Bank and Federal Home Loan Bank Stock	8,918		10,284
Total assets measured at fair value on a recurring basis	104,936		145,322
Noninterest bearing deposits	(188,149)		(170,259)
Interest-bearing deposits	(560,831)		(675,136)
Borrowings	(45,000)		(45,000)
Junior subordinated debentures	(17,527)		(17,527)
Total liabilities measured at fair value on a recurring basis	(811,507)		(907,922)
Derivative Financial Instruments | Level 1 | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	4,233		4,407
Derivative Financial Instruments | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	10,672		55,809
Loans, net	717,818		719,257
Derivative assets - TBA securities	540
Total assets measured at fair value on a recurring basis	793,972		855,475
Derivative liabilities - TBA securities			(158)
Total liabilities measured at fair value on a recurring basis			(158)
Derivative Financial Instruments | Level 2 | Mortgage backed securities issued by U.S. Agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	62,634		78,446
Derivative Financial Instruments | Level 2 | Collateralized Mortgage Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	2,308		1,963
Derivative Financial Instruments | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets - Mortgage servicing rights	3,823		2,801
Derivative assets - IRLC's	81		580
Total assets measured at fair value on a recurring basis	4,679		4,943
Derivative Financial Instruments | Level 3 | Collateralized Mortgage Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value			662
Derivative Financial Instruments | Level 3 | Asset backed security
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale, at fair value	$ 775		$ 900

[1] Secured by closed-end first lien 1-4 family residential mortgages.

[2] Comprised of a security that represents an interest in a pool of trust preferred securities issued by U.S.-based banks and insurance companies.

[3] Consists primarily of mutual fund investments in closed-end first lien 1-4 family residential mortgages.