Loans and the Allowance for Loan Losses - (Details 8) - Receivables Acquired with Deteriorated Credit Quality - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014	Sep. 01, 2013
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		$ 292,100	$ 344,425	$ 899,236
Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		15,358	8,004
Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		106,268	135,037
Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		170,474	201,384
Commercial, financial, agricultural
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		11,920	23,404
Commercial, financial, agricultural | Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		15	0
Commercial, financial, agricultural | Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		3,711	6,684
Commercial, financial, agricultural | Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		8,194	16,720
Lease financing
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Lease financing | Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Lease financing | Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Lease financing | Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Real estate – construction
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Real estate – construction | Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Real estate – construction | Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Real estate – construction | Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Real estate – 1-4 family mortgage
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		75,349	82,819
Real estate – 1-4 family mortgage | Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		3,233	420
Real estate – 1-4 family mortgage | Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		37,100	43,597
Real estate – 1-4 family mortgage | Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		35,016	38,802
Real estate – commercial mortgage
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		201,699	234,245
Real estate – commercial mortgage | Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		12,110	7,584
Real estate – commercial mortgage | Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		65,426	84,720
Real estate – commercial mortgage | Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		124,163	141,941
Installment loans to individuals
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality	[1]	3,132	3,957
Installment loans to individuals | Impaired Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		0	0
Installment loans to individuals | Other Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		31	36
Installment loans to individuals | Not Covered Loans
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality		$ 3,101	$ 3,921
Contractually-required principal and interest
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality				1,112,979
Nonaccretable difference
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality				70,334
Cash flows expected to be collected
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality				1,042,645
Accretable yield
Loans acquired with deteriorated credit quality
Acquired with deteriorated credit quality				$ 143,409

[1] Includes lease financing receivables.