Fair Value Disclosures - Assets, Liabilities and Off-balance Sheet Items Not Measured at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets:
Held-to-maturity securities	$ 66,853	$ 71,327
Deposits:
Time deposits	270,789	331,511
Reported Value Measurement [Member]
Assets:
Cash and short-term interest-earning assets	69,169	146,112
Held-to-maturity securities	66,003	69,845
Loans held for sale	2,267	4,530
Net loans and leases held for investment	1,461,620	1,412,140
Mortgage servicing rights	5,519
Other real estate owned	1,650
Total assets	1,606,228	1,632,627
Deposits:
Demand and savings deposits, non-maturity	1,573,709	1,533,822
Time deposits	270,789	331,511
Total deposits	1,844,498	1,865,333
Short-term borrowings	37,256	96,282
Long-term borrowings		20,994
Total liabilities	1,881,754	1,982,609
Off-Balance-Sheet:
Commitments to extend credit
Estimate of Fair Value Measurement [Member]
Assets:
Cash and short-term interest-earning assets	69,169	146,112
Held-to-maturity securities	66,853	71,327
Loans held for sale	2,267	4,653
Net loans and leases held for investment	1,477,945	1,433,990
Mortgage servicing rights	7,188
Other real estate owned	1,650
Total assets	1,625,072	1,656,082
Deposits:
Demand and savings deposits, non-maturity	1,573,709	1,533,822
Time deposits	268,909	334,164
Total deposits	1,842,618	1,867,986
Short-term borrowings	35,687	94,066
Long-term borrowings		20,965
Total liabilities	1,878,305	1,983,017
Off-Balance-Sheet:
Commitments to extend credit	(1,357)	(1,286)
Estimate of Fair Value Measurement [Member] | Level 1 [Member]
Assets:
Cash and short-term interest-earning assets	69,169	146,112
Held-to-maturity securities
Loans held for sale
Net loans and leases held for investment
Mortgage servicing rights
Other real estate owned
Total assets	69,169	146,112
Deposits:
Demand and savings deposits, non-maturity	1,573,709	1,533,822
Time deposits
Total deposits	1,573,709	1,533,822
Short-term borrowings
Long-term borrowings
Total liabilities	1,573,709	1,533,822
Off-Balance-Sheet:
Commitments to extend credit
Estimate of Fair Value Measurement [Member] | Level 2 [Member]
Assets:
Cash and short-term interest-earning assets
Held-to-maturity securities	66,853	71,327
Loans held for sale	2,267	4,653
Net loans and leases held for investment
Mortgage servicing rights	7,188
Other real estate owned	1,650
Total assets	77,958	75,980
Deposits:
Demand and savings deposits, non-maturity
Time deposits	268,909	334,164
Total deposits	268,909	334,164
Short-term borrowings	35,687	94,066
Long-term borrowings		20,965
Total liabilities	304,596	449,195
Off-Balance-Sheet:
Commitments to extend credit	(1,357)	(1,286)
Estimate of Fair Value Measurement [Member] | Level 3 [Member]
Assets:
Cash and short-term interest-earning assets
Held-to-maturity securities
Loans held for sale
Net loans and leases held for investment	1,477,945	1,433,990
Mortgage servicing rights
Other real estate owned
Total assets	1,477,945	1,433,990
Deposits:
Demand and savings deposits, non-maturity
Time deposits
Total deposits
Short-term borrowings
Long-term borrowings
Total liabilities
Off-Balance-Sheet:
Commitments to extend credit