Age Analysis of Past Due Financing receivables (Details) $ in Thousands	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($) loan	Dec. 31, 2013 USD ($)
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	377	396
Number of Loans 60-89 Days | loan	48	57
Number of Loans 90 Days or More | loan	87	117
Number of Loans Total Past Due | loan	512	570
Principal Balance Total Past Due	$ 31,057	$ 39,758
Current	5,516,664	4,930,975
Loans and Leases Receivable, Gross	5,547,721	4,970,733	$ 4,718,307	[1]
Total Financing Receivables	5,547,721	4,970,733
Recorded Investment >90 Days and Accruing	$ 0	$ 119
Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	9	18
Number of Loans 60-89 Days | loan	4	10
Number of Loans 90 Days or More | loan	8	19
Number of Loans Total Past Due | loan	21	47
Principal Balance Total Past Due	$ 4,459	$ 6,519
Current	838,817	854,320
Loans and Leases Receivable, Gross	843,276	860,839	784,202
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	19	19
Number of Loans 60-89 Days | loan	6	6
Number of Loans 90 Days or More | loan	13	16
Number of Loans Total Past Due | loan	38	41
Principal Balance Total Past Due	$ 13,434	$ 19,133
Current	2,640,000	2,328,190
Loans and Leases Receivable, Gross	2,653,434	2,347,323	2,249,260
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	0	1
Number of Loans 60-89 Days | loan	0	0
Number of Loans 90 Days or More | loan	1	1
Number of Loans Total Past Due | loan	1	2
Principal Balance Total Past Due	$ 304	$ 817
Current	373,064	265,177
Loans and Leases Receivable, Gross	373,368	265,994	223,859
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Small Business [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	11	7
Number of Loans 60-89 Days | loan	4	8
Number of Loans 90 Days or More | loan	13	7
Number of Loans Total Past Due | loan	28	22
Principal Balance Total Past Due	$ 171	$ 307
Current	96,075	84,940
Loans and Leases Receivable, Gross	96,246	85,247	77,240
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	20	13
Number of Loans 60-89 Days | loan	11	10
Number of Loans 90 Days or More | loan	19	36
Number of Loans Total Past Due | loan	50	59
Principal Balance Total Past Due	$ 8,601	$ 8,294
Current	630,005	521,965
Loans and Leases Receivable, Gross	638,606	530,259	541,443
Recorded Investment >90 Days and Accruing	$ 0	$ 106
Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	21	20
Number of Loans 60-89 Days | loan	11	7
Number of Loans 90 Days or More | loan	20	23
Number of Loans Total Past Due | loan	52	50
Principal Balance Total Past Due	$ 3,767	$ 4,268
Current	924,036	859,595
Loans and Leases Receivable, Gross	927,803	863,863	822,141
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	297	318
Number of Loans 60-89 Days | loan	12	16
Number of Loans 90 Days or More | loan	13	15
Number of Loans Total Past Due | loan	322	349
Principal Balance Total Past Due	$ 321	$ 420
Current	14,667	16,788
Loans and Leases Receivable, Gross		17,208	$ 20,162
Total Financing Receivables	14,988
Recorded Investment >90 Days and Accruing	0	13
Financing Receivables, 30 to 59 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	12,717	20,758
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	399	3,192
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	7,349	13,428
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	0	506
Financing Receivables, 30 to 59 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	93	21
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	3,119	1,670
Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	1,526	1,559
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	231	382
Financing Receivables, 60 to 89 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	5,674	4,728
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	1,021	1,007
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	1,627	1,480
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	9	113
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	2,049	1,798
Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	903	307
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	65	23
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	12,666	14,272
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	3,039	2,320
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	4,458	4,225
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	304	311
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	69	173
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	3,433	4,826
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	1,338	2,402
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	$ 25	$ 15

[1] The amount of net deferred fees on loans and net unamortized discounts on acquired loans not deemed to be PCI included in the ending balance was $10.9 million, $4.7 million, and $3.9 million at December 31, 2015, 2014, and 2013, respectively.