Loans and Allowance for Loan Losses - Summary of Loans By Classification (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans and Allowance for Loan Losses
Loans	$ 1,374,660	$ 941,796
Allowance for loan losses	8,311	6,250	$ 5,422	$ 4,458
Loans and Leases Receivable, Net Amount, Total	1,366,349	935,546
Mortgage warehouse lines of credit
Loans and Allowance for Loan Losses
Loans	224,937	275,039
Allowance for loan losses	283	373	704	475
Residential real estate
Loans and Allowance for Loan Losses
Loans	330,410	235,759
Allowance for loan losses	1,587	2,170	2,212	1,806
Multi-family and healthcare financing
Loans and Allowance for Loan Losses
Loans	529,259	261,031
Allowance for loan losses	3,502	1,962	1,308	689
Commercial and commercial real estate
Loans and Allowance for Loan Losses
Loans	228,668	113,812
Allowance for loan losses	2,362	1,374	908	1,163
Agricultural production and real estate
Loans and Allowance for Loan Losses
Loans	51,966	46,763
Allowance for loan losses	320	269	222	275
Consumer and margin loans
Loans and Allowance for Loan Losses
Loans	9,420	9,392
Allowance for loan losses	$ 257	$ 102	$ 68	$ 50

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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