Loans and Allowance for Loan Losses (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	$ 15,970		$ 14,341
90 Days and Greater	4,945		5,903
Total Past Due Loans	20,915		20,244
Current Loans	3,199,052		3,029,132
Total Loans	3,219,967	3,242,427	3,049,376
Accruing Loans 90 Days or More Past Due	542	537	1,150
Non-residential real estate [Member]
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	3,293		3,924
90 Days and Greater	1,945		849
Total Past Due Loans	5,238		4,773
Current Loans	1,238,804		1,097,141
Total Loans	1,244,042		1,101,914
Accruing Loans 90 Days or More Past Due	18		192
Residential real estate [Member]
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	4,438		3,218
90 Days and Greater	868		1,915
Total Past Due Loans	5,306		5,133
Current Loans	768,487		690,937
Total Loans	773,793		696,070
Accruing Loans 90 Days or More Past Due	268		436
Non-consumer non-real estate [Member]
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	2,100		1,311
90 Days and Greater	214		633
Total Past Due Loans	2,314		1,944
Current Loans	748,287		723,144
Total Loans	750,601		725,088
Accruing Loans 90 Days or More Past Due	74		132
Consumer non-real estate [Member]
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	1,994		1,767
90 Days and Greater	184		220
Total Past Due Loans	2,178		1,987
Current Loans	209,142		198,221
Total Loans	211,320		200,208
Accruing Loans 90 Days or More Past Due	126		195
Other loans [Member]
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	2,152		1,414
90 Days and Greater	1,406		1,352
Total Past Due Loans	3,558		2,766
Current Loans	140,468		160,722
Total Loans	144,026		163,488
Accruing Loans 90 Days or More Past Due			59
Acquired loans [Member]
Age analysis of past due loans segregated by class of loans
30-89 Days Past Due	1,993		2,707
90 Days and Greater	328		934
Total Past Due Loans	2,321		3,641
Current Loans	93,864		158,967
Total Loans	96,185		162,608
Accruing Loans 90 Days or More Past Due	$ 56		$ 136