Fair Value of Financial Instruments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Investment securities available for sale [Abstract]
Alternative investments	$ 8,000,000		$ 6,700,000
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Valuation allowance of impaired loans	1,200,000		1,200,000
Other Liabilities [Member]
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, January 1	0		0
Total net realized (losses) gains included in income	0		0
Change in unrealized gains/losses included in other comprehensive income for assets and liabilities still held at December 31	0		0
Purchases	0		0
Issuances	0		0
Settlements	0		0
Transfers out of Level 3	0		0
Fair value, December 31	0		0
Total realized (losses) gains included in income related to financial assets and liabilities still on the consolidated balance sheet at December 31	0		0
Other Assets [Member]
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, January 1	6,701,000		4,681,000
Total net realized (losses) gains included in income	670,000		(344,000)
Change in unrealized gains/losses included in other comprehensive income for assets and liabilities still held at December 31	0		0
Purchases	633,000		2,517,000
Issuances	0		0
Settlements	0		(153,000)
Transfers out of Level 3	0		0
Fair value, December 31	8,004,000		6,701,000
Total realized (losses) gains included in income related to financial assets and liabilities still on the consolidated balance sheet at December 31	670,000		(344,000)
Recurring [Member]
Investment securities available for sale [Abstract]
U.S. government agency securities	113,456,000		103,873,000
Mortgage-backed securities	455,839,000		412,936,000
State and municipal securities	138,578,000		148,411,000
Agency- backed securities	13,018,000		17,007,000
Corporate notes and other	11,163,000		11,229,000
Total investment securities available-for-sale	732,054,000		693,456,000
Alternative investments	8,004,000		6,701,000
Other assets	15,987,000		19,900,000
Total assets at fair value	756,045,000		720,057,000
Liabilities at fair value [Abstract]
Other liabilities	15,981,000		13,670,000
Total liabilities at fair value	15,981,000		13,670,000
Recurring [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Investment securities available for sale [Abstract]
U.S. government agency securities	0		0
Mortgage-backed securities	0		0
State and municipal securities	0		0
Agency- backed securities			0
Corporate notes and other	0		0
Total investment securities available-for-sale	0		0
Alternative investments	0		0
Other assets	0		0
Total assets at fair value	0		0
Liabilities at fair value [Abstract]
Other liabilities	0		0
Total liabilities at fair value	0		0
Recurring [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Investment securities available for sale [Abstract]
U.S. government agency securities	113,456,000		103,873,000
Mortgage-backed securities	455,839,000		412,936,000
State and municipal securities	138,578,000		148,411,000
Agency- backed securities	13,018,000		17,007,000
Corporate notes and other	11,163,000		11,229,000
Total investment securities available-for-sale	732,054,000		693,456,000
Alternative investments	0		0
Other assets	15,987,000		19,900,000
Total assets at fair value	748,041,000		713,356,000
Liabilities at fair value [Abstract]
Other liabilities	15,981,000		13,670,000
Total liabilities at fair value	15,981,000		13,670,000
Recurring [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Investment securities available for sale [Abstract]
U.S. government agency securities	0		0
Mortgage-backed securities	0		0
State and municipal securities	0		0
Agency- backed securities			0
Corporate notes and other	0		0
Total investment securities available-for-sale	0		0
Alternative investments	8,004,000		6,701,000
Other assets	0		0
Total assets at fair value	8,004,000		6,701,000
Liabilities at fair value [Abstract]
Other liabilities	0		0
Total liabilities at fair value	0		0
Nonrecurring [Member]
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned	11,186,000		15,226,000
Nonperforming loans, net	15,550,000	[1]	16,996,000	[1]
Total	26,736,000		32,222,000
Gain (losses) on Other real estate owned	(509,000)		(2,258,000)
Gain (losses) on Impaired loans, net	(1,032,000)	[1]	(2,921,000)	[1]
Total gains (losses)	(1,541,000)		(5,179,000)
Nonrecurring [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned	0		0
Nonperforming loans, net	0	[1]	0	[1]
Total	0		0
Nonrecurring [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned	0		0
Nonperforming loans, net	0	[1]	0	[1]
Total	0		0
Nonrecurring [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Assets and liabilities measured at fair value on a nonrecurring basis [Abstract]
Other real estate owned	11,186,000		15,226,000
Nonperforming loans, net	15,550,000	[1]	16,996,000	[1]
Total	$ 26,736,000		$ 32,222,000

[1] Amount is net of a valuation allowance of $1.2 million at both December 31, 2014 and 2013, respectively, as required by ASC 310-10, "Receivables."