Fair Value Measurement - Summary of Assets Measured at Fair Value on Non-recurring Basis, Excluding Acquired Impaired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Commercial Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	$ 12,783	$ 8,916
Residential Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	2,271	1,007
Commercial and Industrial
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	12,092	986
Other Real Estate Owned
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	10,626	16,570
Level 3 | Commercial Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	12,783	8,916
Level 3 | Residential Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	2,271	1,007
Level 3 | Commercial and Industrial
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	12,092	986
Level 3 | Other Real Estate Owned
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	10,626	16,570
Assets Held For Sale
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	9,779	14,748
Assets Held For Sale | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	$ 9,779	$ 14,748