Loans and Allowance for Loan Losses - Allowance For Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Allowance for loan losses
Balance, beginning of period	$ 9,705	$ 6,550	$ 8,311	$ 6,250
Provision for loan losses	(998)	(240)	2,404	480
Loans charged to the allowance	(146)		(163)
Recoveries of loans previously charged off	31	75	36	135
Balance, end of period	10,588	6,865	10,588	6,865
Ending balance: individually evaluated for impairment	541		541		$ 362
Ending balance: collectively evaluated for impairment	10,047		10,047		7,949
Loans
Ending balance	1,834,279		1,834,279		1,374,660
Ending balance individually evaluated for impairment	9,351		9,351		7,336
Ending balance: collectively evaluated for impairment	1,824,928		1,824,928		1,367,324
Mortgage warehouse lines of credit
Allowance for loan losses
Balance, beginning of period	506	181	283	373
Provision for loan losses	(140)	(100)	363	(92)
Balance, end of period	646	281	646	281
Ending balance: individually evaluated for impairment	175		175
Ending balance: collectively evaluated for impairment	471		471		283
Loans
Ending balance	397,852		397,852		224,937
Ending balance individually evaluated for impairment	804		804
Ending balance: collectively evaluated for impairment	397,048		397,048		224,937
Residential real estate
Allowance for loan losses
Balance, beginning of period	1,664	1,928	1,587	2,170
Provision for loan losses	(133)	(10)	209	(232)
Recoveries of loans previously charged off	15		16
Balance, end of period	1,812	1,938	1,812	1,938
Ending balance: collectively evaluated for impairment	1,812		1,812		1,587
Loans
Ending balance	380,228		380,228		330,410
Ending balance individually evaluated for impairment	1,066		1,066		729
Ending balance: collectively evaluated for impairment	379,162		379,162		329,681
Multi-family and healthcare financing
Allowance for loan losses
Balance, beginning of period	4,250	2,097	3,502	1,962
Provision for loan losses	(412)	(329)	1,160	464
Balance, end of period	4,662	2,426	4,662	2,426
Ending balance: collectively evaluated for impairment	4,662		4,662		3,502
Loans
Ending balance	703,305		703,305		529,259
Ending balance individually evaluated for impairment	110		110
Ending balance: collectively evaluated for impairment	703,195		703,195		529,259
Commercial and commercial real estate
Allowance for loan losses
Balance, beginning of period	2,685	1,918	2,362	1,374
Provision for loan losses	(252)	148	575	370
Loans charged to the allowance	(135)		(135)
Recoveries of loans previously charged off	1	75	1	101
Balance, end of period	2,803	1,845	2,803	1,845
Ending balance: individually evaluated for impairment	200		200		200
Ending balance: collectively evaluated for impairment	2,603		2,603		2,162
Loans
Ending balance	271,661		271,661		228,668
Ending balance individually evaluated for impairment	6,539		6,539		6,179
Ending balance: collectively evaluated for impairment	265,122		265,122		222,489
Agricultural production and real estate
Allowance for loan losses
Balance, beginning of period	333	306	320	269
Provision for loan losses	(59)	35	72	2
Balance, end of period	392	271	392	271
Ending balance: individually evaluated for impairment	20		20		16
Ending balance: collectively evaluated for impairment	372		372		304
Loans
Ending balance	69,204		69,204		51,966
Ending balance individually evaluated for impairment	636		636		282
Ending balance: collectively evaluated for impairment	68,568		68,568		51,684
Consumer and margin loans
Allowance for loan losses
Balance, beginning of period	267	120	257	102
Provision for loan losses	(2)	16	25	(32)
Loans charged to the allowance	(11)		(28)
Recoveries of loans previously charged off	15		19	34
Balance, end of period	273	$ 104	273	$ 104
Ending balance: individually evaluated for impairment	146		146		146
Ending balance: collectively evaluated for impairment	127		127		111
Loans
Ending balance	12,029		12,029		9,420
Ending balance individually evaluated for impairment	196		196		146
Ending balance: collectively evaluated for impairment	$ 11,833		$ 11,833		$ 9,274

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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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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Amount of expense related to estimated loss from loan and lease transactions.

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