Loans - Outstanding Principal and Carrying Amount of Acquired Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Outstanding principal balance and the carrying amount of loan acquired [Abstract]
Outstanding principal balance	$ 73,058	$ 79,523
Carrying amount	67,685	73,796
Outstanding principal balance and the carrying amount of loan acquired, impaired [Abstract]
Outstanding principal balance	26,229	27,876
Carrying amount	$ 22,034	$ 23,430