Loans and Allowance for Loan Losses - Aging Analysis Of The Recorded Investment In Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Aging analysis of loan portfolio
Past due loans	$ 8,876	$ 12,608
Current loans	4,144,936	3,015,702
Loans and Leases Receivable, Net of Deferred Income, Total	4,153,812	3,028,310
30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	1,913	7,479
60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	614	928
Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	6,349	4,201
Mortgage warehouse lines of credit
Aging analysis of loan portfolio
Current loans	1,287,246	765,151
Loans and Leases Receivable, Net of Deferred Income, Total	1,287,246	765,151
Residential real estate
Aging analysis of loan portfolio
Past due loans	863	5,975
Current loans	470,944	407,860
Loans and Leases Receivable, Net of Deferred Income, Total	471,807	413,835
Residential real estate | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	165	3,089
Residential real estate | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	138	562
Residential real estate | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	560	2,324
Multi-family and healthcare financing
Aging analysis of loan portfolio
Current loans	1,848,811	1,347,125
Loans and Leases Receivable, Net of Deferred Income, Total	1,848,811	1,347,125
Commercial and commercial real estate
Aging analysis of loan portfolio
Past due loans	4,640	4,291
Current loans	427,582	394,310
Loans and Leases Receivable, Net of Deferred Income, Total	432,222	398,601
Commercial and commercial real estate | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	1,522	2,293
Commercial and commercial real estate | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	368	335
Commercial and commercial real estate | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	2,750	1,663
Agricultural production and real estate
Aging analysis of loan portfolio
Past due loans	2,726	2,242
Current loans	96,309	82,968
Loans and Leases Receivable, Net of Deferred Income, Total	99,035	85,210
Agricultural production and real estate | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	212	2,047
Agricultural production and real estate | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	97
Agricultural production and real estate | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	2,417	195
Consumer and margin loans
Aging analysis of loan portfolio
Past due loans	647	100
Current loans	14,044	18,288
Loans and Leases Receivable, Net of Deferred Income, Total	14,691	18,388
Consumer and margin loans | 30-59 Days Past Due
Aging analysis of loan portfolio
Past due loans	14	50
Consumer and margin loans | 60-89 Days Past Due
Aging analysis of loan portfolio
Past due loans	11	31
Consumer and margin loans | Greater Than 90 Days
Aging analysis of loan portfolio
Past due loans	$ 622	$ 19