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	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Loans:
Loans	$ 4,238,205		$ 3,924,865
Allowance for loan losses	(62,550)	$ (62,801)	(63,964)	$ (68,367)	$ (69,583)	$ (67,870)
Net Loans	4,175,655		3,860,901
Commercial and industrial loans
Loans:
Loans	984,223		896,688
Agricultural production financing and other loans to farmers
Loans:
Loans	93,695		104,927
Real estate loans - Construction
Loans:
Loans	256,082		207,221
Real estate loans - Commercial and farmland
Loans:
Loans	1,705,647		1,672,661
Real estate loans - Residential
Loans:
Loans	689,621		647,315
Allowance for loan losses	(12,311)	(13,269)	(13,152)	(14,928)	(13,908)	(15,077)
Real estate loans - Home Equity
Loans:
Loans	302,403		286,529
Individuals' loans for household and other personal expenditures
Loans:
Loans	62,785		73,400
Allowance for loan losses	(2,927)	(3,138)	(2,658)	$ (2,243)	$ (2,410)	$ (2,515)
Lease financing receivables, net of unearned income
Loans:
Loans	742		1,106
Allowance for loan losses	(5)	$ (4)	(3)
Other commercial loans
Loans:
Loans	$ 143,007		$ 35,018