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Summary of Significant Accounting Policies - Dividend (Details) - USD ($)		12 Months Ended
	Jan. 16, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 15, 2019
90-Days or Greater Past Due Loans
Period from due date after which accrual of interest income is discontinued		90 days
Accumulated other comprehensive income (loss) breakdown
Unrealized gains on securities		$ 4,000,000
Unrealized losses on securities			$ 2,200,000
Unrealized Loss on Price Risk Cash Flow Derivatives, before Tax		41,000	760,000
Goodwill and Core Deposit Intangible
Impairment of goodwill		0
Amortization of core deposit intangible		387,000	96,000	$ 16,000
Core Deposit Intangible
Goodwill and Core Deposit Intangible
Amortization of core deposit intangible		387,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Estimated future amortization expense for the core deposit intangible for the year ending December 31, 2020		483,000
Estimated future amortization expense for the core deposit intangible for the year ending December 31, 2021		416,000
Estimated future amortization expense for the core deposit intangible for the year ending December 31, 2022		380,000
Estimated future amortization expense for the core deposit intangible for the year ending December 31, 2023		372,000
Estimated future amortization expense for the core deposit intangible for the year ending December 31, 2024		372,000
Core Deposit Intangible \| Talmer
Goodwill and Core Deposit Intangible
Remaining intangible asset		$ 465,000
Core Deposit Intangible \| GCFC/ABC Bank
Goodwill and Core Deposit Intangible
Useful life (in years)		10 years
Intangible asset recorded		$ 3,100,000
Remaining intangible asset		2,700,000
Subsequent Event
Subsequent Events
Dividends Payable, Amount Per Share					$ 0.01
Warrants to purchase shares of common stock	815,339
Exercise price of warrant	$ 13.43
Market price per share	$ 14.23
Number os shares issued	45,836
Reduction in additional paid up capital	$ 313,000
All other
Allowance for Loan Losses
Unallocated component of allowance		$ 537,000	$ 542,000	$ 435,000