Earnings per Share (EPS) and Common Stock - Earnings Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Earnings Per Share And Common Stock [Abstract]
Net Income (Loss)	$ 162,644	$ 114,445	$ 244,876	$ 180,832
Weighted-average shares outstanding—Basic	120,177	119,587	120,210	119,354
Dilutive effect of restricted stock units	677	1,125	790	1,126
Weighted-average shares outstanding—Diluted	120,854	120,712	121,000	120,480
Earnings per share—Basic	$ 1.35	$ 0.96	$ 2.04	$ 1.52
Earnings per share—Diluted	$ 1.35	$ 0.95	$ 2.02	$ 1.5