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Allowance for Loan Losses - Summary of Allowance for Loan Losses and Recorded Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	$ 35		$ 77
Allowance for Loan Losses, Collectively Evaluated for Impairment	60,482		56,313
Total Allowance for Loan Losses	60,517	$ 59,046	56,390	$ 55,351	$ 55,816	$ 52,775
Portfolio Loans, Individually Evaluated for Impairment	33,765		26,823
Portfolio Loans, Collectively Evaluated for Impairment	5,752,353		5,734,626
Total Portfolio Loans	5,786,118		5,761,449
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	31,232		27,235
Total Allowance for Loan Losses	31,232	30,963	27,235	24,358	20,570	19,976
Portfolio Loans, Individually Evaluated for Impairment	3,555		3,546
Portfolio Loans, Collectively Evaluated for Impairment	2,785,086		2,682,448
Total Portfolio Loans			2,685,994
Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0		29
Allowance for Loan Losses, Collectively Evaluated for Impairment	10,874		8,937
Total Allowance for Loan Losses	10,874	10,472	8,966	9,256	13,244	10,810
Portfolio Loans, Individually Evaluated for Impairment	17,539		7,284
Portfolio Loans, Collectively Evaluated for Impairment	1,438,039		1,425,982
Total Portfolio Loans			1,433,266
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	11,676		13,167
Total Allowance for Loan Losses	11,676	10,721	13,167	13,944	14,102	13,999
Portfolio Loans, Individually Evaluated for Impairment	3,441		5,464
Portfolio Loans, Collectively Evaluated for Impairment	296,346		378,870
Total Portfolio Loans			384,334
Consumer real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0		21
Allowance for Loan Losses, Collectively Evaluated for Impairment	5,241		5,458
Total Allowance for Loan Losses	5,241	5,418	5,479	5,803	5,956	6,095
Portfolio Loans, Individually Evaluated for Impairment	9,186		10,488
Portfolio Loans, Collectively Evaluated for Impairment	1,166,288		1,180,163
Total Portfolio Loans	1,175,474		1,190,651
Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	35		27
Allowance for Loan Losses, Collectively Evaluated for Impairment	1,459		1,516
Total Allowance for Loan Losses	1,494	$ 1,472	1,543	$ 1,990	$ 1,944	$ 1,895
Portfolio Loans, Individually Evaluated for Impairment	44		41
Portfolio Loans, Collectively Evaluated for Impairment	66,594		67,163
Total Portfolio Loans	$ 66,638		$ 67,204

X

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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