Allowance for Loan Losses and Credit Quality of Loans, Past Due Loans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Aging [Abstract]
Minimum number of days past due for nonaccrual loan status (in days)	90 days
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	$ 31,961	$ 22,852
61 - 90 Days Past Due Accruing	5,894	5,277
Greater Than 90 Days Past Due Accruing	3,737	2,448
Total Past Due Accruing	41,592	30,577
Non-Accrual	49,965	39,676
Current	5,315,238	4,207,363
Recorded Total Loans and Leases	5,406,795	4,277,616
Commercial Loans [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		0
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		0
Total Past Due Accruing		0
Non-Accrual		4,985
Current		556,496
Recorded Total Loans and Leases		561,481
Commercial Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		126
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		0
Total Past Due Accruing		126
Non-Accrual		7,977
Current		966,692
Recorded Total Loans and Leases		974,795
Commercial Loans [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		22
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		0
Total Past Due Accruing		22
Non-Accrual		699
Current		63,037
Recorded Total Loans and Leases		63,758
Commercial Loans [Member] | Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		108
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		103
Total Past Due Accruing		211
Non-Accrual		1,038
Current		36,128
Recorded Total Loans and Leases		37,377
Commercial Loans [Member] | Business Banking [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		3,019
61 - 90 Days Past Due Accruing		708
Greater Than 90 Days Past Due Accruing		45
Total Past Due Accruing		3,772
Non-Accrual		6,738
Current		355,450
Recorded Total Loans and Leases		365,960
Commercial Loans [Member] | Total Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		3,275
61 - 90 Days Past Due Accruing		708
Greater Than 90 Days Past Due Accruing		148
Total Past Due Accruing		4,131
Non-Accrual		21,437
Current		1,977,803
Recorded Total Loans and Leases		2,003,371
Consumer Loans [Member] | Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		10,956
61 - 90 Days Past Due Accruing		2,477
Greater Than 90 Days Past Due Accruing		1,205
Total Past Due Accruing		14,638
Non-Accrual		1,557
Current		964,802
Recorded Total Loans and Leases		980,997
Consumer Loans [Member] | Home Equity Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		6,065
61 - 90 Days Past Due Accruing		1,223
Greater Than 90 Days Past Due Accruing		681
Total Past Due Accruing		7,969
Non-Accrual		7,247
Current		560,066
Recorded Total Loans and Leases		575,282
Consumer Loans [Member] | Direct [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		717
61 - 90 Days Past Due Accruing		144
Greater Than 90 Days Past Due Accruing		84
Total Past Due Accruing		945
Non-Accrual		266
Current		65,648
Recorded Total Loans and Leases		66,859
Consumer Loans [Member] | Total Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		17,738
61 - 90 Days Past Due Accruing		3,844
Greater Than 90 Days Past Due Accruing		1,970
Total Past Due Accruing		23,552
Non-Accrual		9,070
Current		1,590,516
Recorded Total Loans and Leases		1,623,138
Residential Real Estate Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		1,839
61 - 90 Days Past Due Accruing		725
Greater Than 90 Days Past Due Accruing		330
Total Past Due Accruing		2,894
Non-Accrual		9,169
Current		639,044
Recorded Total Loans and Leases		651,107
Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	28,124
61 - 90 Days Past Due Accruing	5,660
Greater Than 90 Days Past Due Accruing	3,657
Total Past Due Accruing	37,441
Non-Accrual	33,883	39,676
Current	4,405,079
Recorded Total Loans and Leases	4,476,403
Originated Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	19,300	21,437
Originated Loans [Member] | Commercial Loans [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	105
61 - 90 Days Past Due Accruing	247
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	352
Non-Accrual	3,669	4,985
Current	612,402
Recorded Total Loans and Leases	616,423
Originated Loans [Member] | Commercial Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,366
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	1,366
Non-Accrual	7,834	7,977
Current	925,116
Recorded Total Loans and Leases	934,316
Originated Loans [Member] | Commercial Loans [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	150
61 - 90 Days Past Due Accruing	21
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	171
Non-Accrual	1,135	699
Current	63,856
Recorded Total Loans and Leases	65,162
Originated Loans [Member] | Commercial Loans [Member] | Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	519
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	519
Non-Accrual	961	1,038
Current	35,172
Recorded Total Loans and Leases	36,652
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,228
61 - 90 Days Past Due Accruing	122
Greater Than 90 Days Past Due Accruing	105
Total Past Due Accruing	1,455
Non-Accrual	5,701	6,738
Current	330,523
Recorded Total Loans and Leases	337,679
Originated Loans [Member] | Commercial Loans [Member] | Total Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	3,368
61 - 90 Days Past Due Accruing	390
Greater Than 90 Days Past Due Accruing	105
Total Past Due Accruing	3,863
Non-Accrual	19,300
Current	1,967,069
Recorded Total Loans and Leases	1,990,232
Originated Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	7,478	9,070
Originated Loans [Member] | Consumer Loans [Member] | Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	14,093
61 - 90 Days Past Due Accruing	2,878
Greater Than 90 Days Past Due Accruing	1,583
Total Past Due Accruing	18,554
Non-Accrual	1,461	1,557
Current	1,141,829
Recorded Total Loans and Leases	1,161,844
Originated Loans [Member] | Consumer Loans [Member] | Home Equity Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	6,033
61 - 90 Days Past Due Accruing	1,888
Greater Than 90 Days Past Due Accruing	1,115
Total Past Due Accruing	9,036
Non-Accrual	5,931	7,247
Current	517,856
Recorded Total Loans and Leases	532,823
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	679
61 - 90 Days Past Due Accruing	125
Greater Than 90 Days Past Due Accruing	46
Total Past Due Accruing	850
Non-Accrual	86	266
Current	57,347
Recorded Total Loans and Leases	58,283
Originated Loans [Member] | Consumer Loans [Member] | Total Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	20,805
61 - 90 Days Past Due Accruing	4,891
Greater Than 90 Days Past Due Accruing	2,744
Total Past Due Accruing	28,440
Non-Accrual	7,478
Current	1,717,032
Recorded Total Loans and Leases	1,752,950
Originated Loans [Member] | Residential Real Estate Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	3,951
61 - 90 Days Past Due Accruing	379
Greater Than 90 Days Past Due Accruing	808
Total Past Due Accruing	5,138
Non-Accrual	7,105	9,169
Current	720,978
Recorded Total Loans and Leases	733,221
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	3,837
61 - 90 Days Past Due Accruing	234
Greater Than 90 Days Past Due Accruing	80
Total Past Due Accruing	4,151
Non-Accrual	16,082
Current	910,159
Recorded Total Loans and Leases	930,392
Acquired Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	11,498
Acquired Loans [Member] | Commercial Loans [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	24
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	24
Non-Accrual	6,599
Current	96,603
Recorded Total Loans and Leases	103,226
Acquired Loans [Member] | Commercial Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	0
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	0
Non-Accrual	3,559
Current	225,455
Recorded Total Loans and Leases	229,014
Acquired Loans [Member] | Commercial Loans [Member] | Business Banking [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	320
61 - 90 Days Past Due Accruing	2
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	322
Non-Accrual	1,340
Current	68,487
Recorded Total Loans and Leases	70,149
Acquired Loans [Member] | Commercial Loans [Member] | Total Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	344
61 - 90 Days Past Due Accruing	2
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	346
Non-Accrual	11,498
Current	390,545
Recorded Total Loans and Leases	402,389
Acquired Loans [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	712
Acquired Loans [Member] | Consumer Loans [Member] | Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	939
61 - 90 Days Past Due Accruing	113
Greater Than 90 Days Past Due Accruing	71
Total Past Due Accruing	1,123
Non-Accrual	93
Current	123,870
Recorded Total Loans and Leases	125,086
Acquired Loans [Member] | Consumer Loans [Member] | Home Equity Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	753
61 - 90 Days Past Due Accruing	63
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	816
Non-Accrual	570
Current	85,690
Recorded Total Loans and Leases	87,076
Acquired Loans [Member] | Consumer Loans [Member] | Direct [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	76
61 - 90 Days Past Due Accruing	56
Greater Than 90 Days Past Due Accruing	9
Total Past Due Accruing	141
Non-Accrual	49
Current	7,235
Recorded Total Loans and Leases	7,425
Acquired Loans [Member] | Consumer Loans [Member] | Total Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,768
61 - 90 Days Past Due Accruing	232
Greater Than 90 Days Past Due Accruing	80
Total Past Due Accruing	2,080
Non-Accrual	712
Current	216,795
Recorded Total Loans and Leases	219,587
Acquired Loans [Member] | Residential Real Estate Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,725
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	1,725
Non-Accrual	3,872
Current	302,819
Recorded Total Loans and Leases	$ 308,416