CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 89,361	$ 86,248
Other comprehensive income, net of tax
Adjustment to postemployment benefit obligation, net of tax of $(217) and $(96), respectively	759	234
Other comprehensive income	759	234
Comprehensive income	$ 90,120	$ 86,482