Allowance for Loan Losses and Credit Quality of Loans, Past Due Loans (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Aging [Abstract]
Minimum number of days past due for nonaccrual loan status	90 days
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	$ 24,899	$ 31,961
61 - 90 Days Past Due Accruing	4,517	5,894
Greater Than 90 Days Past Due Accruing	2,186	3,737
Total Past Due Accruing	31,602	41,592
Non-Accrual	51,234	49,965
Current	5,491,652	5,315,238
Ending balance of loans	5,574,488	5,406,795
Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	21,621	28,124
61 - 90 Days Past Due Accruing	4,193	5,660
Greater Than 90 Days Past Due Accruing	2,085	3,657
Total Past Due Accruing	27,899	37,441
Non-Accrual	36,351	33,883
Current	4,664,090	4,405,079
Ending balance of loans	4,728,340	4,476,403
ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	3,278	3,837
61 - 90 Days Past Due Accruing	324	234
Greater Than 90 Days Past Due Accruing	101	80
Total Past Due Accruing	3,703	4,151
Non-Accrual	14,883	16,082
Current	827,562	910,159
Ending balance of loans	846,148	930,392
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Ending balance of loans	2,476,246	2,392,621
Commercial Loans [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,096	3,368
61 - 90 Days Past Due Accruing	451	390
Greater Than 90 Days Past Due Accruing	0	105
Total Past Due Accruing	1,547	3,863
Non-Accrual	19,442	19,300
Current	2,077,767	1,967,069
Ending balance of loans	2,098,756	1,990,232
Commercial Loans [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,037	344
61 - 90 Days Past Due Accruing	0	2
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	1,037	346
Non-Accrual	10,722	11,498
Current	365,731	390,545
Ending balance of loans	377,490	402,389
Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	53	105
61 - 90 Days Past Due Accruing	0	247
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	53	352
Non-Accrual	3,885	3,669
Current	653,268	612,402
Ending balance of loans	657,206	616,423
Commercial [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	14	24
61 - 90 Days Past Due Accruing	0	0
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	14	24
Non-Accrual	6,339	6,599
Current	92,335	96,603
Ending balance of loans	98,688	103,226
Commercial Real Estate [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	0	1,366
61 - 90 Days Past Due Accruing	0	0
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	0	1,366
Non-Accrual	6,616	7,834
Current	994,773	925,116
Ending balance of loans	1,001,389	934,316
Commercial Real Estate [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	582	0
61 - 90 Days Past Due Accruing	0	0
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	582	0
Non-Accrual	3,429	3,559
Current	210,204	225,455
Ending balance of loans	214,215	229,014
Agricultural [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	170	150
61 - 90 Days Past Due Accruing	0	21
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	170	171
Non-Accrual	1,343	1,135
Current	55,572	63,856
Ending balance of loans	57,085	65,162
Agricultural Real Estate [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	4	519
61 - 90 Days Past Due Accruing	0	0
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	4	519
Non-Accrual	1,590	961
Current	40,768	35,172
Ending balance of loans	42,362	36,652
Business Banking [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	869	1,228
61 - 90 Days Past Due Accruing	451	122
Greater Than 90 Days Past Due Accruing	0	105
Total Past Due Accruing	1,320	1,455
Non-Accrual	6,008	5,701
Current	333,386	330,523
Ending balance of loans	340,714	337,679
Business Banking [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	441	320
61 - 90 Days Past Due Accruing	0	2
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	441	322
Non-Accrual	954	1,340
Current	63,192	68,487
Ending balance of loans	64,587	70,149
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Ending balance of loans	2,025,035	1,972,537
Consumer Loans [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	17,443	20,805
61 - 90 Days Past Due Accruing	3,148	4,891
Greater Than 90 Days Past Due Accruing	1,966	2,744
Total Past Due Accruing	22,557	28,440
Non-Accrual	9,198	7,478
Current	1,814,027	1,717,032
Ending balance of loans	1,845,782	1,752,950
Consumer Loans [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	924	1,768
61 - 90 Days Past Due Accruing	324	232
Greater Than 90 Days Past Due Accruing	101	80
Total Past Due Accruing	1,349	2,080
Non-Accrual	663	712
Current	177,241	216,795
Ending balance of loans	179,253	219,587
Indirect [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	12,444	14,093
61 - 90 Days Past Due Accruing	2,015	2,878
Greater Than 90 Days Past Due Accruing	1,100	1,583
Total Past Due Accruing	15,559	18,554
Non-Accrual	1,359	1,461
Current	1,265,140	1,141,829
Ending balance of loans	1,282,058	1,161,844
Indirect [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	481	939
61 - 90 Days Past Due Accruing	114	113
Greater Than 90 Days Past Due Accruing	54	71
Total Past Due Accruing	649	1,123
Non-Accrual	118	93
Current	91,212	123,870
Ending balance of loans	91,979	125,086
Home Equity Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	4,470	6,033
61 - 90 Days Past Due Accruing	995	1,888
Greater Than 90 Days Past Due Accruing	839	1,115
Total Past Due Accruing	6,304	9,036
Non-Accrual	7,772	5,931
Current	494,123	517,856
Ending balance of loans	508,199	532,823
Home Equity Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	370	753
61 - 90 Days Past Due Accruing	204	63
Greater Than 90 Days Past Due Accruing	36	0
Total Past Due Accruing	610	816
Non-Accrual	514	570
Current	80,068	85,690
Ending balance of loans	81,192	87,076
Direct [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	529	679
61 - 90 Days Past Due Accruing	138	125
Greater Than 90 Days Past Due Accruing	27	46
Total Past Due Accruing	694	850
Non-Accrual	67	86
Current	54,764	57,347
Ending balance of loans	55,525	58,283
Direct [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	73	76
61 - 90 Days Past Due Accruing	6	56
Greater Than 90 Days Past Due Accruing	11	9
Total Past Due Accruing	90	141
Non-Accrual	31	49
Current	5,961	7,235
Ending balance of loans	6,082	7,425
Residential Real Estate Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Ending balance of loans	1,073,207	1,041,637
Residential Real Estate Mortgages [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	3,082	3,951
61 - 90 Days Past Due Accruing	594	379
Greater Than 90 Days Past Due Accruing	119	808
Total Past Due Accruing	3,795	5,138
Non-Accrual	7,711	7,105
Current	772,296	720,978
Ending balance of loans	783,802	733,221
Residential Real Estate Mortgages [Member] | ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,317	1,725
61 - 90 Days Past Due Accruing	0	0
Greater Than 90 Days Past Due Accruing	0	0
Total Past Due Accruing	1,317	1,725
Non-Accrual	3,498	3,872
Current	284,590	302,819
Ending balance of loans	$ 289,405	$ 308,416