Loans and Allowance - Allowance for Credit Losses and Loan Portfolio by Loan Segment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	$ 1,326		$ 1,354
Allowance balances - Collectively evaluated for impairment	66,659		66,287
Allowance balances - Loans acquired with deteriorated credit quality	382		229
Total Allowance for Loan Losses	68,367	69,583	67,870	68,202	68,537	69,366
Loan balances - Individually evaluated for impairment	42,311		42,067
Loan balances - Collectively evaluated for impairment	3,609,504		3,511,501
Loan balances - Loans acquired with deteriorated credit quality	70,918		78,841
Loans	3,722,733		3,632,409
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	886		585
Allowance balances - Collectively evaluated for impairment	27,671		26,493
Allowance balances - Loans acquired with deteriorated credit quality	57		98
Total Allowance for Loan Losses	28,614	30,907	27,176	26,563	25,371	25,913
Loan balances - Individually evaluated for impairment	7,895		10,240
Loan balances - Collectively evaluated for impairment	966,594		882,794
Loan balances - Loans acquired with deteriorated credit quality	7,683		7,548
Loans	982,172		900,582
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	440		763
Allowance balances - Collectively evaluated for impairment	21,817		22,208
Allowance balances - Loans acquired with deteriorated credit quality	325		131
Total Allowance for Loan Losses	22,582	22,358	23,102	23,605	24,978	26,703
Loan balances - Individually evaluated for impairment	31,543		29,007
Loan balances - Collectively evaluated for impairment	1,693,600		1,690,285
Loan balances - Loans acquired with deteriorated credit quality	61,681		69,599
Loans	1,786,824		1,788,891
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Collectively evaluated for impairment	2,243		2,515
Total Allowance for Loan Losses	2,243	2,410	2,515	2,885	2,689	2,593
Loan balances - Collectively evaluated for impairment	61,533		69,783
Loans	61,533		69,783
Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment			6
Allowance balances - Collectively evaluated for impairment	14,928		15,071
Total Allowance for Loan Losses	14,928	13,908	15,077	15,113	15,479	14,157
Loan balances - Individually evaluated for impairment	2,873		2,820
Loan balances - Collectively evaluated for impairment	886,546		867,094
Loan balances - Loans acquired with deteriorated credit quality	1,554		1,694
Loans	890,973		871,608
Finance Leases
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Allowance for Loan Losses				36	20
Loan balances - Collectively evaluated for impairment	1,231		1,545
Loans	$ 1,231		$ 1,545