Loans - Summarizes Changes in Total Contractually Required Principal and Interest Cash Payments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2014
Schedule of Contractually Required Principal And Interest Cash Payments Changes [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	$ 0	$ 2,610	$ 1,192
Additions	1,256	2,052	702
Deletions	(50)	(15)	(357)
Accretion	(96)	(1,734)	(601)
Reclassifications from nonaccretable difference	82	894	1,674
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	1,192	3,807	2,610
Carrying value		453,686	332,321
Purchased Credit Impaired Loan [Member]
Schedule of Contractually Required Principal And Interest Cash Payments Changes [Line Items]
Carrying value	7,814	12,996	12,109	$ 0
Allowance for loan losses	(64)	0	0	0
Carrying value less allowance for loan losses	$ 7,750	$ 12,996	$ 12,109	$ 0