Loans and Allowance for Loan Losses - Credit risk profile by risk grade of acquired loans - (Details 9) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	$ 1,049,538	$ 1,327,999
Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	1,022,135	1,292,782
Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	7,369	14,815
Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	20,034	20,402
Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	737,576	926,767	$ 1,232,256
Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	414,572	470,384
Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	142,378	154,568
Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	180,626	301,815
Commercial Loans Greater Than or Equal to $1 Million-CBT | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	12,628	15,813	24,109
Commercial Loans Greater Than or Equal to $1 Million-CBT | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	11,238	11,248
Commercial Loans Greater Than or Equal to $1 Million-CBT | Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	1,018	1,030
Commercial Loans Greater Than or Equal to $1 Million-CBT | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	372	3,535
Commercial Loans Greater Than or Equal to $1 Million-CBT | Acquired credit impaired loans | Doubtful
Loans and Allowance for Loan Losses
Total acquired loans	12,628	15,813
Residential real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	313,319	390,244	481,247
Residential real estate | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	166,309	190,931
Residential real estate | Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	63,341	73,699
Residential real estate | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	83,669	125,614
Commercial non-owner occupied real estate | Construction and land development | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	13,849	24,099
Commercial non-owner occupied real estate | Construction and land development | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	12,935	22,456
Commercial non-owner occupied real estate | Construction and land development | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	109	816
Commercial non-owner occupied real estate | Construction and land development | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	805	827
Commercial non-owner occupied real estate | Construction and land development | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	54,272	65,262	114,126
Commercial non-owner occupied real estate | Construction and land development | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	26,308	26,855
Commercial non-owner occupied real estate | Construction and land development | Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	14,532	9,539
Commercial non-owner occupied real estate | Construction and land development | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	13,432	28,868
Commercial non-owner occupied real estate | Construction and land development | Acquired credit impaired loans | Doubtful
Loans and Allowance for Loan Losses
Total acquired loans	54,272	65,262
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	40,103	49,476
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	33,485	42,572
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	637	6,039
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	5,981	865
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	255,430	325,109	439,785
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	177,656	208,269
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	37,607	35,896
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	40,167	80,944
Commercial non-owner occupied real estate | Other commercial non-owner occupied real estate | Acquired credit impaired loans | Doubtful
Loans and Allowance for Loan Losses
Total acquired loans	255,430	325,109
Consumer real estate | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	879,722	1,086,090
Consumer real estate | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	862,688	1,063,844
Consumer real estate | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	5,488	6,351
Consumer real estate | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	11,546	15,895
Consumer real estate | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	70,734	85,449	103,998
Consumer real estate | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	10,703	7,493
Consumer real estate | Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	23,331	29,087
Consumer real estate | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	36,700	48,869
Consumer real estate | Consumer owner occupied | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	518,107	646,375
Consumer real estate | Consumer owner occupied | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	514,817	639,555
Consumer real estate | Consumer owner occupied | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	557	1,241
Consumer real estate | Consumer owner occupied | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	2,733	5,579
Consumer real estate | Home equity loans | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	190,968	234,949
Consumer real estate | Home equity loans | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	180,472	222,653
Consumer real estate | Home equity loans | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	4,202	4,491
Consumer real estate | Home equity loans | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	6,294	7,805
Consumer real estate | Other Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	170,647	204,766
Consumer real estate | Other Consumer | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	167,399	201,636
Consumer real estate | Other Consumer | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	729	619
Consumer real estate | Other Consumer | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	2,519	2,511
Commercial owner occupied real estate | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	39,220	62,065
Commercial owner occupied real estate | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	38,623	61,040
Commercial owner occupied real estate | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	377	265
Commercial owner occupied real estate | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	220	760
Commercial and industrial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	25,475	41,130
Commercial and industrial | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	24,621	39,780
Commercial and industrial | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	166	448
Commercial and industrial | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	688	902
Commercial and industrial | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	31,193	44,804	68,862
Commercial and industrial | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	22,358	25,530
Commercial and industrial | Acquired credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	2,549	5,317
Commercial and industrial | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	6,286	13,957
Single pay | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans		86	$ 129
Single pay | Acquired credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans		58
Single pay | Acquired credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans		28
Other income producing property | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	51,169	65,139
Other income producing property | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	49,783	63,090
Other income producing property | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	592	896
Other income producing property | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	794	1,153
Consumer | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	170,647	204,766
Consumer | Acquired credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	70,734	85,449
Commercial | Acquired non-credit impaired loans
Loans and Allowance for Loan Losses
Total acquired loans	169,816	241,909
Commercial | Acquired non-credit impaired loans | Pass
Loans and Allowance for Loan Losses
Total acquired loans	159,447	228,938
Commercial | Acquired non-credit impaired loans | Special mention
Loans and Allowance for Loan Losses
Total acquired loans	1,881	8,464
Commercial | Acquired non-credit impaired loans | Substandard
Loans and Allowance for Loan Losses
Total acquired loans	$ 8,488	$ 4,507