Loans and the Allowance for Loan Losses (Details) - Aging analysis - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	$ 12,790	$ 5,734
Total Past Due and Nonaccrual	23,992	20,551
Current	3,550,837	3,458,890
Total Loans Receivable	3,574,829	3,479,441
30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	5,328	7,534
60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	451	1,990
90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	5,423	5,293
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,208	1,460
Total Past Due and Nonaccrual	6,631	6,583
Current	535,059	546,993
Total Loans Receivable	541,690	553,576
Commercial Portfolio Segment [Member] | 30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual		475
Commercial Portfolio Segment [Member] | 60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual		18
Commercial Portfolio Segment [Member] | 90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	5,423	4,630
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	7,487	1,081
Total Past Due and Nonaccrual	11,580	8,256
Current	2,315,254	2,196,454
Total Loans Receivable	2,326,834	2,204,710
Commercial Real Estate Portfolio Segment [Member] | 30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	3,649	4,928
Commercial Real Estate Portfolio Segment [Member] | 60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	444	1,584
Commercial Real Estate Portfolio Segment [Member] | 90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual		663
Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual
Total Past Due and Nonaccrual
Current	460,611	486,228
Total Loans Receivable	460,611	486,228
Construction Loans [Member] | 30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual
Construction Loans [Member] | 60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual
Construction Loans [Member] | 90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	4,095	3,193
Total Past Due and Nonaccrual	5,711	5,712
Current	237,112	226,835
Total Loans Receivable	242,883	232,547
Residential Portfolio Segment [Member] | 30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	1,670	2,131
Residential Portfolio Segment [Member] | 60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	6	388
Residential Portfolio Segment [Member] | 90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual
Total Past Due and Nonaccrual	10
Current	2,801	2,380
Total Loans Receivable	2,811	2,380
Consumer Portfolio Segment [Member] | 30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	9
Consumer Portfolio Segment [Member] | 60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual	1
Consumer Portfolio Segment [Member] | 90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Nonaccrual