Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Loans and Allowance - Composition of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Loans:
Loans	$ 4,321,715		$ 3,924,865
Allowance for loan losses	(62,861)	$ (62,550)	(63,964)	$ (65,596)	$ (68,367)	$ (67,870)
Net Loans	4,258,854		3,860,901
Commercial and industrial loans
Loans:
Loans	999,195		896,688
Agricultural production financing and other loans to farmers
Loans:
Loans	91,354		104,927
Real estate loans - Construction
Loans:
Loans	298,250		207,221
Real estate loans - Commercial and farmland
Loans:
Loans	1,695,703		1,672,661
Real estate loans - Residential
Loans:
Loans	677,767		647,315
Allowance for loan losses	(12,213)	(12,311)	(13,152)	(14,207)	(14,928)	(15,077)
Real estate loans - Home Equity
Loans:
Loans	318,949		286,529
Individuals' loans for household and other personal expenditures
Loans:
Loans	71,893		73,400
Allowance for loan losses	(2,723)	(2,927)	(2,658)	(2,228)	$ (2,243)	$ (2,515)
Lease financing receivables, net of unearned income
Loans:
Loans	614		1,106
Allowance for loan losses	(3)	$ (5)	(3)	$ (1)
Other commercial loans
Loans:
Loans	$ 167,990		$ 35,018