Loan and Lease Financings (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	$ 3,969,357	$ 3,632,003
90 Days or More Past Due and Accruing	122	982
Total Accruing Loans	3,981,974	3,653,972
Nonaccrual	12,718	34,602
Total loans and leases	3,994,692	3,688,574
Increase in interest income	1,030	3,030	$ 2,930
Commercial and agricultural
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	740,335	696,351
Total Accruing Loans	740,466	696,474
Nonaccrual	4,283	14,284
Total loans and leases	744,749	710,758
Auto and light truck
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	424,997	397,815
Total Accruing Loans	425,190	397,864
Nonaccrual	46	38
Total loans and leases	425,236	397,902
Medium and heavy duty truck
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	278,254	247,097
Total Accruing Loans	278,254	247,097
Nonaccrual	0	56
Total loans and leases	278,254	247,153
Aircraft financing
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	764,074	699,054
Total Accruing Loans	773,624	715,192
Nonaccrual	4,388	12,473
Total loans and leases	778,012	727,665
Construction equipment financing
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	454,993	396,821
Total Accruing Loans	455,026	399,189
Nonaccrual	539	751
Total loans and leases	455,565	399,940
Commercial real estate
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	698,514	611,780
Total Accruing Loans	698,876	611,780
Nonaccrual	1,392	4,807
Total loans and leases	700,268	616,587
Residential real estate
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	460,771	441,508
90 Days or More Past Due and Accruing	71	873
Total Accruing Loans	462,307	443,791
Nonaccrual	1,822	1,968
Total loans and leases	464,129	445,759
Consumer
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Current	147,419	141,577
90 Days or More Past Due and Accruing	51	109
Total Accruing Loans	148,231	142,585
Nonaccrual	248	225
Total loans and leases	148,479	142,810
30 to 59 Days Past Due
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	11,649	3,363
30 to 59 Days Past Due | Commercial and agricultural
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	52	0
30 to 59 Days Past Due | Auto and light truck
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	170	48
30 to 59 Days Past Due | Medium and heavy duty truck
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	0	0
30 to 59 Days Past Due | Aircraft financing
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	9,442	541
30 to 59 Days Past Due | Construction equipment financing
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	33	999
30 to 59 Days Past Due | Commercial real estate
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	362	0
30 to 59 Days Past Due | Residential real estate
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	1,038	1,099
30 to 59 Days Past Due | Consumer
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	552	676
60 to 89 Days Past Due
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	846	17,624
60 to 89 Days Past Due | Commercial and agricultural
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	79	123
60 to 89 Days Past Due | Auto and light truck
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	23	1
60 to 89 Days Past Due | Medium and heavy duty truck
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	0	0
60 to 89 Days Past Due | Aircraft financing
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	108	15,597
60 to 89 Days Past Due | Construction equipment financing
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	0	1,369
60 to 89 Days Past Due | Commercial real estate
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	0	0
60 to 89 Days Past Due | Residential real estate
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	427	311
60 to 89 Days Past Due | Consumer
Recorded investment of loans and leases, segregated by class, with delinquency aging and nonaccrual status
Past Due	$ 209	$ 223