Non Purchased Loans - Summary of Non-purchased Loans and Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Summary of loans
Gross loans	$ 7,623,663	$ 6,205,118
Unearned income	(3,341)	(2,409)
Loans, net of unearned income	7,620,322	6,202,709
Commercial, financial, agricultural
Summary of loans
Gross loans	1,039,393	717,490
Loans, net of unearned income	1,039,393	717,490
Lease financing
Summary of loans
Gross loans	57,354	49,250
Real estate – construction
Summary of loans
Gross loans	633,389	552,679
Loans, net of unearned income	633,389	552,679
Real estate – 1-4 family mortgage
Summary of loans
Gross loans	2,343,721	1,878,177
Loans, net of unearned income	2,343,721	1,878,177
Real estate – commercial mortgage
Summary of loans
Gross loans	3,427,530	2,898,895
Loans, net of unearned income	3,427,530	2,898,895
Installment loans to individuals
Summary of loans
Gross loans	122,276	108,627
Loans, net of unearned income	176,289	155,468
Non-Purchased
Summary of loans
Gross loans	5,591,897	4,715,981
Unearned income	(3,341)	(2,409)
Loans, net of unearned income	5,588,556	4,713,572
Non-Purchased \| Commercial, financial, agricultural
Summary of loans
Gross loans	763,823	589,290
Non-Purchased \| Lease financing
Summary of loans
Gross loans	57,354	49,250
Non-Purchased \| Real estate – construction
Summary of loans
Gross loans	547,658	483,926
Non-Purchased \| Real estate – 1-4 family mortgage
Summary of loans
Gross loans	1,729,534	1,425,730
Non-Purchased \| Real estate – commercial mortgage
Summary of loans
Gross loans	2,390,076	2,075,137
Non-Purchased \| Installment loans to individuals
Summary of loans
Gross loans	$ 103,452	$ 92,648

Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10152-111534

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=84173941&loc=d3e5074-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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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
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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