Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 49,738	$ 41,854	$ 48,685	$ 41,449
Charge-offs	(2,951)	(2,734)	(4,556)	(4,738)
Recoveries	2,851	820	3,442	1,558
Provision	2,118	5,674	4,185	7,345
Ending Balance	51,756	45,614	51,756	45,614
Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	16,374	11,688	16,095	11,909
Charge-offs	(249)	(682)	(347)	(956)
Recoveries	143	111	319	431
Provision	(743)	1,947	(542)	1,680
Ending Balance	15,525	13,064	15,525	13,064
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	20,495	16,635	19,532	15,898
Charge-offs	(1,103)	(371)	(1,415)	(704)
Recoveries	2,443	370	2,589	496
Provision	1,133	974	2,262	1,918
Ending Balance	22,968	17,608	22,968	17,608
Agricultural
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	4,028	3,216	3,887	3,295
Charge-offs	0	(275)	0	(551)
Recoveries	4	2	7	24
Provision	68	733	206	908
Ending Balance	4,100	3,676	4,100	3,676
Residential real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	1,851	3,745	1,934	3,741
Charge-offs	(105)	(55)	(142)	(113)
Recoveries	4	70	24	107
Provision	315	339	249	364
Ending Balance	2,065	4,099	2,065	4,099
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	6,990	6,570	7,237	6,606
Charge-offs	(1,494)	(1,351)	(2,652)	(2,414)
Recoveries	257	267	503	500
Provision	1,345	1,681	2,010	2,475
Ending Balance	$ 7,098	$ 7,167	$ 7,098	$ 7,167