Loans and Allowance for Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Internal loan grading by class of loans
Total loans	$ 3,242,427	$ 3,013,498
Grade 1 [Member]
Internal loan grading by class of loans
Total loans	2,791,300	2,606,271
Grade 2 [Member]
Internal loan grading by class of loans
Total loans	375,584	319,558
Grade 3 [Member]
Internal loan grading by class of loans
Total loans	56,130	67,150
Grade 4 [Member]
Internal loan grading by class of loans
Total loans	19,413	20,519
Grade 5 [Member]
Internal loan grading by class of loans
Total loans
Non-residential real estate [Member]
Internal loan grading by class of loans
Total loans	1,222,245	1,051,198
Non-residential real estate [Member] \| Grade 1 [Member]
Internal loan grading by class of loans
Total loans	1,020,247	907,687
Non-residential real estate [Member] \| Grade 2 [Member]
Internal loan grading by class of loans
Total loans	165,232	104,614
Non-residential real estate [Member] \| Grade 3 [Member]
Internal loan grading by class of loans
Total loans	27,110	30,519
Non-residential real estate [Member] \| Grade 4 [Member]
Internal loan grading by class of loans
Total loans	9,656	8,378
Non-residential real estate [Member] \| Grade 5 [Member]
Internal loan grading by class of loans
Total loans
Residential real estate [Member]
Internal loan grading by class of loans
Total loans	754,933	694,623
Residential real estate [Member] \| Grade 1 [Member]
Internal loan grading by class of loans
Total loans	648,877	599,337
Residential real estate [Member] \| Grade 2 [Member]
Internal loan grading by class of loans
Total loans	86,564	74,480
Residential real estate [Member] \| Grade 3 [Member]
Internal loan grading by class of loans
Total loans	15,382	15,567
Residential real estate [Member] \| Grade 4 [Member]
Internal loan grading by class of loans
Total loans	4,110	5,239
Residential real estate [Member] \| Grade 5 [Member]
Internal loan grading by class of loans
Total loans
Non-consumer non-real estate [Member]
Internal loan grading by class of loans
Total loans	785,123	726,690
Non-consumer non-real estate [Member] \| Grade 1 [Member]
Internal loan grading by class of loans
Total loans	684,740	626,735
Non-consumer non-real estate [Member] \| Grade 2 [Member]
Internal loan grading by class of loans
Total loans	92,784	91,497
Non-consumer non-real estate [Member] \| Grade 3 [Member]
Internal loan grading by class of loans
Total loans	6,084	7,399
Non-consumer non-real estate [Member] \| Grade 4 [Member]
Internal loan grading by class of loans
Total loans	1,515	1,059
Non-consumer non-real estate [Member] \| Grade 5 [Member]
Internal loan grading by class of loans
Total loans
Consumer non-real estate [Member]
Internal loan grading by class of loans
Total loans	221,747	200,216
Consumer non-real estate [Member] \| Grade 1 [Member]
Internal loan grading by class of loans
Total loans	209,182	188,180
Consumer non-real estate [Member] \| Grade 2 [Member]
Internal loan grading by class of loans
Total loans	10,305	9,229
Consumer non-real estate [Member] \| Grade 3 [Member]
Internal loan grading by class of loans
Total loans	1,904	2,431
Consumer non-real estate [Member] \| Grade 4 [Member]
Internal loan grading by class of loans
Total loans	356	376
Consumer non-real estate [Member] \| Grade 5 [Member]
Internal loan grading by class of loans
Total loans
Other loans [Member]
Internal loan grading by class of loans
Total loans	149,897	159,043
Other loans [Member] \| Grade 1 [Member]
Internal loan grading by class of loans
Total loans	145,239	152,798
Other loans [Member] \| Grade 2 [Member]
Internal loan grading by class of loans
Total loans	2,575	2,546
Other loans [Member] \| Grade 3 [Member]
Internal loan grading by class of loans
Total loans	1,172	1,653
Other loans [Member] \| Grade 4 [Member]
Internal loan grading by class of loans
Total loans	911	2,046
Other loans [Member] \| Grade 5 [Member]
Internal loan grading by class of loans
Total loans
Acquired loans [Member]
Internal loan grading by class of loans
Total loans	108,482	181,728
Acquired loans [Member] \| Grade 1 [Member]
Internal loan grading by class of loans
Total loans	83,015	131,534
Acquired loans [Member] \| Grade 2 [Member]
Internal loan grading by class of loans
Total loans	18,124	37,192
Acquired loans [Member] \| Grade 3 [Member]
Internal loan grading by class of loans
Total loans	4,478	9,581
Acquired loans [Member] \| Grade 4 [Member]
Internal loan grading by class of loans
Total loans	2,865	3,421
Acquired loans [Member] \| Grade 5 [Member]
Internal loan grading by class of loans
Total loans