Loans and Allowance for Loan Losses - Disaggregated analysis of activity in the allowance for acquired credit impaired loans (Details 7) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for loan losses:
Provision for loan losses before benefit attributable to FDIC loss share agreements	$ 5,078,000	$ 4,170,000	$ 100,000
Benefits attributable to FDIC loss share agreements	786,000	2,420,000	1,786,000
Total provision for loan losses charged to operations	5,864,000	6,590,000	1,886,000
Provision for loan losses recorded through the FDIC loss share receivable	(786,000)	(2,420,000)	(1,786,000)
Reduction due to loan removals	(3,407,000)	(2,346,000)	(4,682,000)
Balance at the end of the period	0
Non-acquired loans
Allowance for loan losses:
Provision for loan losses before benefit attributable to FDIC loss share agreements	2,930,000	5,150,000	1,018,000
Total provision for loan losses charged to operations	2,930,000	5,150,000	1,018,000
Loans individually evaluated for impairment	1,607,000	1,558,000	1,631,000
Loans collectively evaluated for impairment	32,483,000	32,981,000	32,700,000
Loans:
Loans individually evaluated for impairment	30,218,000	27,085,000	26,047,000
Loans collectively evaluated for impairment	4,190,508,000	3,440,741,000	2,839,169,000
Acquired non-credit impaired loans
Allowance for loan losses:
Provision for loan losses before benefit attributable to FDIC loss share agreements	2,400,000	927,000
Total provision for loan losses charged to operations	2,400,000	927,000
Loans:
Loans collectively evaluated for impairment	1,049,538,000	1,327,999,000
Total acquired loans	1,049,538,000	1,327,999,000
Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	7,365,000	11,618,000	17,218,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	(252,000)	(1,907,000)	(918,000)
Benefits attributable to FDIC loss share agreements	786,000	2,420,000	1,786,000
Total provision for loan losses charged to operations	534,000	513,000	868,000
Provision for loan losses recorded through the FDIC loss share receivable	(786,000)	(2,420,000)	(1,786,000)
Reduction due to loan removals	(3,407,000)	(2,346,000)	(4,682,000)
Balance at the end of the period	3,706,000	7,365,000	11,618,000
Loans collectively evaluated for impairment	3,706,000	7,365,000	11,618,000
Loans:
Loans collectively evaluated for impairment	737,576,000	926,767,000	1,232,256,000
Total acquired loans	737,576,000	926,767,000	1,232,256,000
Commercial Loans Greater Than or Equal to $1 Million-CBT | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	135,000	303,000	5,337,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	(43,000)	(129,000)	(3,109,000)
Benefits attributable to FDIC loss share agreements		183,000	2,934,000
Total provision for loan losses charged to operations	(43,000)	54,000	(175,000)
Provision for loan losses recorded through the FDIC loss share receivable		(183,000)	(2,934,000)
Reduction due to loan removals	(92,000)	(39,000)	(1,925,000)
Balance at the end of the period		135,000	303,000
Loans collectively evaluated for impairment		135,000	303,000
Loans:
Loans collectively evaluated for impairment	12,628,000	15,813,000	24,109,000
Total acquired loans	12,628,000	15,813,000	24,109,000
Residential real estate | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	4,387,000	5,132,000	4,207,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	99,000	(406,000)	1,057,000
Benefits attributable to FDIC loss share agreements	228,000	571,000	(520,000)
Total provision for loan losses charged to operations	327,000	165,000	537,000
Provision for loan losses recorded through the FDIC loss share receivable	(228,000)	(571,000)	520,000
Reduction due to loan removals	(1,500,000)	(339,000)	(132,000)
Balance at the end of the period	2,986,000	4,387,000	5,132,000
Loans collectively evaluated for impairment	2,986,000	4,387,000	5,132,000
Loans:
Loans collectively evaluated for impairment	313,319,000	390,244,000	481,247,000
Total acquired loans	313,319,000	390,244,000	481,247,000
Commercial non-owner occupied real estate | Construction and land development | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	(1,707,000)	(1,307,000)	(786,000)
Loans individually evaluated for impairment	615,000	475,000	704,000
Loans collectively evaluated for impairment	3,501,000	5,191,000	6,085,000
Loans:
Loans individually evaluated for impairment	6,280,000	4,852,000	5,739,000
Loans collectively evaluated for impairment	395,699,000	359,369,000	294,212,000
Commercial non-owner occupied real estate | Construction and land development | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	(4,000)	77,000
Loans:
Loans collectively evaluated for impairment	13,849,000	24,099,000
Total acquired loans	13,849,000	24,099,000
Commercial non-owner occupied real estate | Construction and land development | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	336,000	2,244,000	1,628,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	(68,000)	(621,000)	2,347,000
Benefits attributable to FDIC loss share agreements	74,000	792,000	(1,645,000)
Total provision for loan losses charged to operations	6,000	171,000	702,000
Provision for loan losses recorded through the FDIC loss share receivable	(74,000)	(792,000)	1,645,000
Reduction due to loan removals	(91,000)	(1,287,000)	(1,731,000)
Balance at the end of the period	177,000	336,000	2,244,000
Loans collectively evaluated for impairment	177,000	336,000	2,244,000
Loans:
Loans collectively evaluated for impairment	54,272,000	65,262,000	114,126,000
Total acquired loans	54,272,000	65,262,000	114,126,000
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	503,000	(471,000)	(937,000)
Loans individually evaluated for impairment	34,000	77,000
Loans collectively evaluated for impairment	3,534,000	3,077,000	3,677,000
Loans:
Loans individually evaluated for impairment	1,452,000	3,610,000	2,681,000
Loans collectively evaluated for impairment	486,325,000	329,980,000	288,490,000
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations		72,000
Loans:
Loans collectively evaluated for impairment	40,103,000	49,476,000
Total acquired loans	40,103,000	49,476,000
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	1,444,000	1,816,000	1,517,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	(456,000)	(328,000)	299,000
Benefits attributable to FDIC loss share agreements	459,000	364,000	(456,000)
Total provision for loan losses charged to operations	3,000	36,000	(157,000)
Provision for loan losses recorded through the FDIC loss share receivable	(459,000)	(364,000)	456,000
Reduction due to loan removals	(932,000)	(44,000)
Balance at the end of the period	56,000	1,444,000	1,816,000
Loans collectively evaluated for impairment	56,000	1,444,000	1,816,000
Loans:
Loans collectively evaluated for impairment	255,430,000	325,109,000	439,785,000
Total acquired loans	255,430,000	325,109,000	439,785,000
Consumer real estate | Acquired non-credit impaired loans
Loans:
Total acquired loans	879,722,000	1,086,090,000
Consumer real estate | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	275,000	538,000	96,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	336,000	(111,000)	442,000
Benefits attributable to FDIC loss share agreements	(107,000)	141,000	(412,000)
Total provision for loan losses charged to operations	229,000	30,000	30,000
Provision for loan losses recorded through the FDIC loss share receivable	107,000	(141,000)	412,000
Reduction due to loan removals	(298,000)	(152,000)
Balance at the end of the period	313,000	275,000	538,000
Loans collectively evaluated for impairment	313,000	275,000	538,000
Loans:
Loans collectively evaluated for impairment	70,734,000	85,449,000	103,998,000
Total acquired loans	70,734,000	85,449,000	103,998,000
Consumer real estate | Consumer owner occupied | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	577,000	908,000	330,000
Loans individually evaluated for impairment	138,000	144,000	271,000
Loans collectively evaluated for impairment	7,074,000	6,722,000	5,798,000
Loans:
Loans individually evaluated for impairment	7,549,000	2,966,000	3,013,000
Loans collectively evaluated for impairment	1,011,435,000	783,812,000	545,157,000
Consumer real estate | Consumer owner occupied | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	258,000	130,000
Loans:
Loans collectively evaluated for impairment	518,107,000	646,375,000
Total acquired loans	518,107,000	646,375,000
Consumer real estate | Home equity loans | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	403,000	978,000	147,000
Loans individually evaluated for impairment	3,000	1,000
Loans collectively evaluated for impairment	2,926,000	2,828,000	2,782,000
Loans:
Loans individually evaluated for impairment	309,000	31,000
Loans collectively evaluated for impairment	318,946,000	283,903,000	257,139,000
Consumer real estate | Home equity loans | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	1,425,000	268,000
Loans:
Loans collectively evaluated for impairment	190,968,000	234,949,000
Total acquired loans	190,968,000	234,949,000
Commercial owner occupied real estate | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	746,000	1,084,000	1,678,000
Loans individually evaluated for impairment	101,000	172,000	10,000
Loans collectively evaluated for impairment	8,240,000	8,243,000	7,757,000
Loans:
Loans individually evaluated for impairment	7,725,000	9,160,000	11,560,000
Loans collectively evaluated for impairment	1,025,673,000	898,753,000	821,953,000
Commercial owner occupied real estate | Acquired non-credit impaired loans
Loans:
Loans collectively evaluated for impairment	39,220,000	62,065,000
Total acquired loans	39,220,000	62,065,000
Commercial and industrial | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	(74,000)	819,000	(532,000)
Loans individually evaluated for impairment	279,000	41,000
Loans collectively evaluated for impairment	3,695,000	3,520,000	3,592,000
Loans:
Loans individually evaluated for impairment	1,487,000	908,000	405,000
Loans collectively evaluated for impairment	502,321,000	405,015,000	321,419,000
Commercial and industrial | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	99,000	144,000
Loans:
Loans collectively evaluated for impairment	25,475,000	41,130,000
Total acquired loans	25,475,000	41,130,000
Commercial and industrial | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	718,000	1,481,000	4,139,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	(118,000)	(314,000)	(1,786,000)
Benefits attributable to FDIC loss share agreements	131,000	371,000	1,719,000
Total provision for loan losses charged to operations	13,000	57,000	(67,000)
Provision for loan losses recorded through the FDIC loss share receivable	(131,000)	(371,000)	(1,719,000)
Reduction due to loan removals	(426,000)	(449,000)	(872,000)
Balance at the end of the period	174,000	718,000	1,481,000
Loans collectively evaluated for impairment	174,000	718,000	1,481,000
Loans:
Loans collectively evaluated for impairment	31,193,000	44,804,000	68,862,000
Total acquired loans	31,193,000	44,804,000	68,862,000
Single pay | Acquired credit impaired loans
Allowance for loan losses:
Balance at the beginning of the period	70,000	104,000	294,000
Provision for loan losses before benefit attributable to FDIC loss share agreements	(2,000)	2,000	(168,000)
Benefits attributable to FDIC loss share agreements	1,000	(2,000)	166,000
Total provision for loan losses charged to operations	(1,000)		(2,000)
Provision for loan losses recorded through the FDIC loss share receivable	(1,000)	2,000	(166,000)
Reduction due to loan removals	(68,000)	(36,000)	(22,000)
Balance at the end of the period		70,000	104,000
Loans collectively evaluated for impairment		70,000	104,000
Loans:
Loans collectively evaluated for impairment		86,000	129,000
Total acquired loans		86,000	129,000
Other income producing property | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	(252,000)	(159,000)	(646,000)
Loans individually evaluated for impairment	422,000	646,000	646,000
Loans collectively evaluated for impairment	1,541,000	1,586,000	1,863,000
Loans:
Loans individually evaluated for impairment	4,891,000	5,498,000	2,649,000
Loans collectively evaluated for impairment	170,957,000	145,430,000	140,555,000
Other income producing property | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations		14,000
Loans:
Loans collectively evaluated for impairment	51,169,000	65,139,000
Total acquired loans	51,169,000	65,139,000
Consumer | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	2,890,000	3,058,000	1,772,000
Loans individually evaluated for impairment	3,000	2,000
Loans collectively evaluated for impairment	1,691,000	1,365,000	937,000
Loans:
Loans individually evaluated for impairment	102,000	60,000
Loans collectively evaluated for impairment	233,002,000	189,257,000	136,410,000
Consumer | Acquired non-credit impaired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	622,000	222,000
Loans:
Loans collectively evaluated for impairment	170,647,000	204,766,000
Total acquired loans	170,647,000	204,766,000
Consumer | Acquired credit impaired loans
Loans:
Total acquired loans	70,734,000	85,449,000
Other Loans | Non-acquired loans
Allowance for loan losses:
Total provision for loan losses charged to operations	(156,000)	240,000	(8,000)
Loans individually evaluated for impairment	12,000
Loans collectively evaluated for impairment	281,000	449,000	209,000
Loans:
Loans individually evaluated for impairment	423,000
Loans collectively evaluated for impairment	$ 46,150,000	$ 45,222,000	$ 33,834,000