Allowance for Loan Losses - Summary of Allowance for Loan Losses and Recorded Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	$ 312		$ 798
Allowance for Loan Losses, Collectively Evaluated for Impairment	56,400		51,977
Total Allowance for Loan Losses	56,712	$ 55,351	52,775	$ 53,793	$ 52,213	$ 48,147
Portfolio Loans, Individually Evaluated for Impairment	31,988		41,935
Portfolio Loans, Collectively Evaluated for Impairment	5,788,770		5,569,484
Total Portfolio Loans	5,820,758		5,611,419
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0		0
Allowance for Loan Losses, Collectively Evaluated for Impairment	24,975		19,976
Total Allowance for Loan Losses	24,975	24,358	19,976	20,393	15,978	15,043
Portfolio Loans, Individually Evaluated for Impairment	6,341		16,352
Portfolio Loans, Collectively Evaluated for Impairment	2,675,352		2,482,124
Total Portfolio Loans	2,681,693		2,498,476
Commercial and Industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	260		771
Allowance for Loan Losses, Collectively Evaluated for Impairment	9,454		10,039
Total Allowance for Loan Losses	9,714	9,256	10,810	12,294	14,771	10,853
Portfolio Loans, Individually Evaluated for Impairment	8,543		6,866
Portfolio Loans, Collectively Evaluated for Impairment	1,438,268		1,394,169
Total Portfolio Loans	1,446,811		1,401,035
Commercial Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0		0
Allowance for Loan Losses, Collectively Evaluated for Impairment	14,915		13,999
Total Allowance for Loan Losses	14,915	13,944	13,999	12,911	11,701	12,625
Portfolio Loans, Individually Evaluated for Impairment	5,974		6,613
Portfolio Loans, Collectively Evaluated for Impairment	426,913		449,271
Total Portfolio Loans	432,887		455,884
Consumer Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	22		26
Allowance for Loan Losses, Collectively Evaluated for Impairment	5,509		6,069
Total Allowance for Loan Losses	5,531	5,803	6,095	6,333	8,418	8,400
Portfolio Loans, Individually Evaluated for Impairment	11,076		12,079
Portfolio Loans, Collectively Evaluated for Impairment	1,178,647		1,178,093
Total Portfolio Loans	1,189,723		1,190,172
Other Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	30		1
Allowance for Loan Losses, Collectively Evaluated for Impairment	1,547		1,894
Total Allowance for Loan Losses	1,577	$ 1,990	1,895	$ 1,862	$ 1,345	$ 1,226
Portfolio Loans, Individually Evaluated for Impairment	54		25
Portfolio Loans, Collectively Evaluated for Impairment	69,590		65,827
Total Portfolio Loans	$ 69,644		$ 65,852