Loans and Leases (Allowance for Credit Losses on Financing Reveivables) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending Balance Under ASC 310-10-35	$ 6,717	$ 4,624
Ending Balance Under ASC 450-20	34,968	34,091
Total	41,685	38,715	36,808	42,693
Ending Balance Evaluated for Impairment Under ASC 310-10-35	71,961	83,576
Ending Balance Evaluated for Impairment Under ASC 450-20	3,428,148	2,741,594
Total	3,500,109	2,825,170
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending Balance Under ASC 310-10-35	2,817	1,350
Ending Balance Under ASC 450-20	10,282	10,038
Total	13,099	11,388	10,549
Ending Balance Evaluated for Impairment Under ASC 310-10-35	14,644	9,031
Ending Balance Evaluated for Impairment Under ASC 450-20	935,553	703,277
Total	950,197	712,308
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending Balance Under ASC 310-10-35	818	1,112
Ending Balance Under ASC 450-20	13,334	13,361
Total	14,152	14,473	14,621
Ending Balance Evaluated for Impairment Under ASC 310-10-35	28,299	45,583
Ending Balance Evaluated for Impairment Under ASC 450-20	1,501,384	1,243,601
Total	1,529,683	1,289,184
Agricultural and Agricultural Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending Balance Under ASC 310-10-35	756	109
Ending Balance Under ASC 450-20	2,236	2,029
Total	2,992	2,138	1,763
Ending Balance Evaluated for Impairment Under ASC 310-10-35	16,667	16,128
Ending Balance Evaluated for Impairment Under ASC 450-20	360,068	312,183
Total	376,735	328,311
Residential Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending Balance Under ASC 310-10-35	605	783
Ending Balance Under ASC 450-20	3,115	2,760
Total	3,720	3,543	3,001
Ending Balance Evaluated for Impairment Under ASC 310-10-35	7,214	7,443
Ending Balance Evaluated for Impairment Under ASC 450-20	342,135	242,246
Total	349,349	249,689
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending Balance Under ASC 310-10-35	1,721	1,270
Ending Balance Under ASC 450-20	6,001	5,903
Total	7,722	7,173	6,874
Ending Balance Evaluated for Impairment Under ASC 310-10-35	5,137	5,391
Ending Balance Evaluated for Impairment Under ASC 450-20	289,008	240,287
Total	$ 294,145	$ 245,678