Deposits - Schedule of Deposit Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Banking and Thrift [Abstract]
More than one years to two years	$ 669,610	$ 657,741
More than two years to three years	474,475	338,265
More than three years to four years	169,069	248,779
More than four years	68,184	81,959
More than four years	22,544	31,730
Total term certificate accounts	$ 1,403,882	$ 1,358,474