Investment Securities Available-for-sale Securities (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities
Amortized Cost	$ 621,126,000	$ 628,584,000
Gross Unrealized Gains	10,520,000	21,260,000
Gross Unrealized Losses	25,538,000	10,659,000
Fair Value	606,108,000	639,185,000
Securities of a single issuer, other than US Treasury, government agencies and US government sponsored agencies exceeding 10% of Stockholders' Equity	0
U.S. Treasury and government agencies
Schedule of Available-for-sale Securities
Amortized Cost	20,000	26,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	20,000	26,000
U.S. government sponsored agencies
Schedule of Available-for-sale Securities
Amortized Cost	308,000	486,000
Gross Unrealized Gains	11,000	30,000
Gross Unrealized Losses	0	0
Fair Value	319,000	516,000
States and political subdivisions
Schedule of Available-for-sale Securities
Amortized Cost	50,509,000	42,458,000
Gross Unrealized Gains	1,480,000	3,292,000
Gross Unrealized Losses	1,027,000	82,000
Fair Value	50,962,000	45,668,000
Residential mortgage-backed securities
Schedule of Available-for-sale Securities
Amortized Cost	527,283,000	511,305,000
Gross Unrealized Gains	5,334,000	12,558,000
Gross Unrealized Losses	22,520,000	9,767,000
Fair Value	510,097,000	514,096,000
Commercial mortgage-backed securities
Schedule of Available-for-sale Securities
Amortized Cost	33,256,000	62,129,000
Gross Unrealized Gains	274,000	2,330,000
Gross Unrealized Losses	1,226,000	43,000
Fair Value	32,304,000	64,416,000
Bank-issued trust preferred securities
Schedule of Available-for-sale Securities
Amortized Cost	8,508,000	10,966,000
Gross Unrealized Gains	0	73,000
Gross Unrealized Losses	679,000	682,000
Fair Value	7,829,000	10,357,000
Equity securities
Schedule of Available-for-sale Securities
Amortized Cost	1,242,000	1,214,000
Gross Unrealized Gains	3,421,000	2,977,000
Gross Unrealized Losses	86,000	85,000
Fair Value	$ 4,577,000	$ 4,106,000