Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense	$ 4,610	$ 4,086	$ 20,283	$ 15,400
Federal income tax expense	4,050	3,645	17,819	13,624
State income tax expense	$ 560	$ 441	$ 2,464	$ 1,776