Loans and Allowance for Loan Losses - Aging Analysis Of The Recorded Investment In Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Aging analysis of loan portfolio
Past due loans	$ 10,630	$ 4,175
Current loans	1,198,522	937,621
Loans and Leases Receivable, Net of Deferred Income, Total	1,209,152	941,796
30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	6,229	184
60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	1,526	2,104
Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	2,875	1,887
Mortgage warehouse lines of credit
Aging analysis of loan portfolio
Current loans	233,466	275,039
Loans and Leases Receivable, Net of Deferred Income, Total	233,466	275,039
Residential real estate
Aging analysis of loan portfolio
Past due loans	303	921
Current loans	307,340	234,838
Loans and Leases Receivable, Net of Deferred Income, Total	307,643	235,759
Residential real estate | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	56	40
Residential real estate | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	40
Residential real estate | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	207	881
Multi-family and healthcare financing
Aging analysis of loan portfolio
Past due loans	7,420
Current loans	386,161	261,031
Loans and Leases Receivable, Net of Deferred Income, Total	393,581	261,031
Multi-family and healthcare financing | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	6,130
Multi-family and healthcare financing | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	1,290
Commercial and commercial real estate
Aging analysis of loan portfolio
Past due loans	2,526	2,960
Current loans	207,895	110,852
Loans and Leases Receivable, Net of Deferred Income, Total	210,421	113,812
Commercial and commercial real estate | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	18	43
Commercial and commercial real estate | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	122	2,018
Commercial and commercial real estate | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	2,386	899
Agricultural production and real estate
Aging analysis of loan portfolio
Past due loans	381	294
Current loans	51,544	46,469
Loans and Leases Receivable, Net of Deferred Income, Total	51,925	46,763
Agricultural production and real estate | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	25	101
Agricultural production and real estate | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	74	86
Agricultural production and real estate | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	282	107
Consumer and margin loans
Aging analysis of loan portfolio
Current loans	12,116	9,392
Loans and Leases Receivable, Net of Deferred Income, Total	$ 12,116	$ 9,392