LHFI and Allowance for Loan Losses, LHFI - Summary of LHFI Evaluated for Impairment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	$ 55,312	$ 79,343
LHFI, Collectively Evaluated For Impairment	7,036,073	6,370,126
Total LHFI	7,091,385	6,449,469
Commercial and Industrial Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	7,622	12,104
LHFI, Collectively Evaluated For Impairment	1,335,589	1,258,246
Total LHFI	1,343,211	1,270,350
Consumer Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	31	88
LHFI, Collectively Evaluated For Impairment	169,104	167,876
Total LHFI	169,135	167,964
State and Other Political Subdivision Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	0	0
LHFI, Collectively Evaluated For Impairment	734,615	602,727
Total LHFI	734,615	602,727
Other Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	512	628
LHFI, Collectively Evaluated For Impairment	421,984	346,546
Total LHFI	422,496	347,174
Loans Secured by Real Estate [Member] \| Construction, Land Development and Other Land [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	6,123	13,867
LHFI, Collectively Evaluated For Impairment	818,600	606,010
Total LHFI	824,723	619,877
Loans Secured by Real Estate [Member] \| Secured by 1-4 Family Residential Properties [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	23,079	25,621
LHFI, Collectively Evaluated For Impairment	1,626,422	1,608,776
Total LHFI	1,649,501	1,634,397
Loans Secured by Real Estate [Member] \| Secured by Nonfarm, Nonresidential Properties [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	17,800	25,717
LHFI, Collectively Evaluated For Impairment	1,718,676	1,527,476
Total LHFI	1,736,476	1,553,193
Loans Secured by Real Estate [Member] \| Other Real Estate Secured [Member]
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	145	1,318
LHFI, Collectively Evaluated For Impairment	211,083	252,469
Total LHFI	$ 211,228	$ 253,787

The balance of financing receivables that were collectively evaluated for impairment.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

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The balance of financing receivables that were individually evaluated for impairment.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524

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