Loans and Allowance for Loan Losses (Details 8) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Loans and Allowance for Loan Losses
Non-acquired OREO	$ 35,330,000	$ 32,248,000	$ 27,484,000	$ 18,022,000
Non-acquired loans
Loans and Allowance for Loan Losses
Total loans	2,741,242,000	2,571,003,000	2,517,352,000
Non-acquired OREO	16,600,000	19,100,000	22,400,000
Classified assets	111,500,000	143,200,000	157,500,000
Non-acquired loans | Pass
Loans and Allowance for Loan Losses
Total loans	2,513,093,000	2,293,728,000	2,237,803,000
Non-acquired loans | Special mention
Loans and Allowance for Loan Losses
Total loans	133,225,000	153,142,000	144,455,000
Non-acquired loans | Substandard and doubtful
Loans and Allowance for Loan Losses
Total loans	94,900,000	124,100,000	135,100,000
Non-acquired loans | Substandard
Loans and Allowance for Loan Losses
Total loans	94,870,000	124,108,000	134,991,000
Non-acquired loans | Doubtful
Loans and Allowance for Loan Losses
Total loans	54,000	25,000	103,000
Non-acquired loans | Commercial Total
Loans and Allowance for Loan Losses
Total loans	1,827,005,000	1,761,119,000	1,717,281,000
Non-acquired loans | Commercial Total | Pass
Loans and Allowance for Loan Losses
Total loans	1,658,038,000	1,545,042,000	1,501,045,000
Non-acquired loans | Commercial Total | Special mention
Loans and Allowance for Loan Losses
Total loans	102,714,000	119,893,000	111,680,000
Non-acquired loans | Commercial Total | Substandard
Loans and Allowance for Loan Losses
Total loans	66,222,000	96,184,000	104,477,000
Non-acquired loans | Commercial Total | Doubtful
Loans and Allowance for Loan Losses
Total loans	31,000		79,000
Non-acquired loans | Construction and land development
Loans and Allowance for Loan Losses
Total loans	288,199,000	273,420,000	273,606,000
Non-acquired loans | Construction and land development | Pass
Loans and Allowance for Loan Losses
Total loans	244,321,000	215,793,000	216,801,000
Non-acquired loans | Construction and land development | Special mention
Loans and Allowance for Loan Losses
Total loans	24,775,000	31,670,000	29,894,000
Non-acquired loans | Construction and land development | Substandard
Loans and Allowance for Loan Losses
Total loans	19,103,000	25,957,000	26,867,000
Non-acquired loans | Construction and land development | Doubtful
Loans and Allowance for Loan Losses
Total loans			44,000
Non-acquired loans | Commercial Non-owner Occupied
Loans and Allowance for Loan Losses
Total loans	282,678,000	290,071,000	278,935,000
Non-acquired loans | Commercial Non-owner Occupied | Pass
Loans and Allowance for Loan Losses
Total loans	238,940,000	232,714,000	223,235,000
Non-acquired loans | Commercial Non-owner Occupied | Special mention
Loans and Allowance for Loan Losses
Total loans	35,052,000	38,473,000	34,470,000
Non-acquired loans | Commercial Non-owner Occupied | Substandard
Loans and Allowance for Loan Losses
Total loans	8,686,000	18,884,000	21,230,000
Non-acquired loans | Commercial Owner Occupied
Loans and Allowance for Loan Losses
Total loans	814,259,000	784,152,000	787,623,000
Non-acquired loans | Commercial Owner Occupied | Pass
Loans and Allowance for Loan Losses
Total loans	764,267,000	716,578,000	716,283,000
Non-acquired loans | Commercial Owner Occupied | Special mention
Loans and Allowance for Loan Losses
Total loans	23,871,000	31,800,000	29,565,000
Non-acquired loans | Commercial Owner Occupied | Substandard
Loans and Allowance for Loan Losses
Total loans	26,121,000	35,774,000	41,740,000
Non-acquired loans | Commercial Owner Occupied | Doubtful
Loans and Allowance for Loan Losses
Total loans			35,000
Non-acquired loans | Commercial & Industrial
Loans and Allowance for Loan Losses
Total loans	301,845,000	279,763,000	245,285,000
Non-acquired loans | Commercial & Industrial | Pass
Loans and Allowance for Loan Losses
Total loans	288,945,000	265,148,000	230,317,000
Non-acquired loans | Commercial & Industrial | Special mention
Loans and Allowance for Loan Losses
Total loans	9,734,000	8,626,000	8,996,000
Non-acquired loans | Commercial & Industrial | Substandard
Loans and Allowance for Loan Losses
Total loans	3,135,000	5,989,000	5,972,000
Non-acquired loans | Commercial & Industrial | Doubtful
Loans and Allowance for Loan Losses
Total loans	31,000
Non-acquired loans | Other Income Producing Property
Loans and Allowance for Loan Losses
Total loans	140,024,000	133,713,000	131,832,000
Non-acquired loans | Other Income Producing Property | Pass
Loans and Allowance for Loan Losses
Total loans	121,565,000	114,809,000	114,409,000
Non-acquired loans | Other Income Producing Property | Special mention
Loans and Allowance for Loan Losses
Total loans	9,282,000	9,324,000	8,755,000
Non-acquired loans | Other Income Producing Property | Substandard
Loans and Allowance for Loan Losses
Total loans	9,177,000	9,580,000	8,668,000
Non-acquired loans | Consumer Total
Loans and Allowance for Loan Losses
Total loans	914,237,000	809,884,000	800,071,000
Non-acquired loans | Consumer Total | Pass
Loans and Allowance for Loan Losses
Total loans	855,055,000	748,686,000	736,758,000
Non-acquired loans | Consumer Total | Special mention
Loans and Allowance for Loan Losses
Total loans	30,511,000	33,249,000	32,775,000
Non-acquired loans | Consumer Total | Substandard
Loans and Allowance for Loan Losses
Total loans	28,648,000	27,924,000	30,514,000
Non-acquired loans | Consumer Total | Doubtful
Loans and Allowance for Loan Losses
Total loans	23,000	25,000	24,000
Non-acquired loans | Consumer Owner Occupied
Loans and Allowance for Loan Losses
Total loans	498,734,000	434,503,000	430,825,000
Non-acquired loans | Consumer Owner Occupied | Pass
Loans and Allowance for Loan Losses
Total loans	454,368,000	388,822,000	383,152,000
Non-acquired loans | Consumer Owner Occupied | Special mention
Loans and Allowance for Loan Losses
Total loans	21,444,000	24,515,000	23,556,000
Non-acquired loans | Consumer Owner Occupied | Substandard
Loans and Allowance for Loan Losses
Total loans	22,922,000	21,166,000	24,117,000
Non-acquired loans | Home Equity
Loans and Allowance for Loan Losses
Total loans	255,291,000	255,284,000	255,677,000
Non-acquired loans | Home Equity | Pass
Loans and Allowance for Loan Losses
Total loans	241,624,000	241,184,000	241,278,000
Non-acquired loans | Home Equity | Special mention
Loans and Allowance for Loan Losses
Total loans	8,218,000	7,837,000	8,420,000
Non-acquired loans | Home Equity | Substandard
Loans and Allowance for Loan Losses
Total loans	5,426,000	6,239,000	5,955,000
Non-acquired loans | Home Equity | Doubtful
Loans and Allowance for Loan Losses
Total loans	23,000	24,000	24,000
Non-acquired loans | Consumer
Loans and Allowance for Loan Losses
Total loans	116,312,000	86,934,000	86,729,000
Non-acquired loans | Consumer | Pass
Loans and Allowance for Loan Losses
Total loans	115,163,000	85,517,000	85,488,000
Non-acquired loans | Consumer | Special mention
Loans and Allowance for Loan Losses
Total loans	849,000	897,000	799,000
Non-acquired loans | Consumer | Substandard
Loans and Allowance for Loan Losses
Total loans	300,000	519,000	442,000
Non-acquired loans | Consumer | Doubtful
Loans and Allowance for Loan Losses
Total loans		1,000
Non-acquired loans | Other
Loans and Allowance for Loan Losses
Total loans	43,900,000	33,163,000	26,840,000
Non-acquired loans | Other | Pass
Loans and Allowance for Loan Losses
Total loans	$ 43,900,000	$ 33,163,000	$ 26,840,000