Allowance for Loan and Lease Losses (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 3,429,878	$ 3,395,676
Commercial and industrial, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	859,038	864,070
Commercial real estate, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,481,257	1,458,618
Residential real estate, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,004,999	986,151
Consumer and other, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	54,710	55,267
Finance Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	13,106	12,251
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	16,768	19,319
Originated Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	10,844	10,366
Collectively Evaluated For Impairment	2,890,010	2,831,996
Total	2,900,854	2,842,362
Originated Loans and Leases [Member] | Commercial and industrial, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	1,048	1,283
Collectively Evaluated For Impairment	764,977	765,753
Total	766,025	767,036
Originated Loans and Leases [Member] | Commercial real estate, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	8,872	7,675
Collectively Evaluated For Impairment	1,137,999	1,103,367
Total	1,146,871	1,111,042
Originated Loans and Leases [Member] | Residential real estate, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	924	1,408
Collectively Evaluated For Impairment	920,265	896,453
Total	921,189	897,861
Originated Loans and Leases [Member] | Consumer and other, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively Evaluated For Impairment	53,663	54,172
Total	53,663	54,172
Originated Loans and Leases [Member] | Finance Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively Evaluated For Impairment	13,106	12,251
Total	13,106	12,251
Acquired Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	5,469	2,263
Loans acquired with deteriorated credit quality	31,003	34,410
Collectively Evaluated For Impairment	492,552	516,641
Total	529,024	553,314
Acquired Loans and Leases [Member] | Commercial and industrial, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	1,201	628
Loans acquired with deteriorated credit quality	763	995
Collectively Evaluated For Impairment	91,049	95,411
Total	93,013	97,034
Acquired Loans and Leases [Member] | Commercial real estate, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	3,321	1,195
Loans acquired with deteriorated credit quality	11,569	11,640
Collectively Evaluated For Impairment	319,496	334,741
Total	334,386	347,576
Acquired Loans and Leases [Member] | Residential real estate, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually Evaluated For Impairment	947	440
Loans acquired with deteriorated credit quality	3,657	3,669
Collectively Evaluated For Impairment	79,206	84,181
Total	83,810	88,290
Acquired Loans and Leases [Member] | Consumer and other, total [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively Evaluated For Impairment	1,047	1,095
Total	1,047	1,095
Acquired Loans and Leases [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with deteriorated credit quality	15,014	18,106
Collectively Evaluated For Impairment	1,754	1,213
Total	$ 16,768	$ 19,319