Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2024	Jun. 30, 2023
Basic Earnings Per Share
Net income	$ 165,564	$ 432,023	$ 311,292	$ 137,807	$ 357,671	$ 271,860	$ 908,879	$ 767,338
Less: Income allocated to participating securities	87			83			490	482
Income available to common shareholders	$ 165,477			$ 137,724			$ 908,389	$ 766,856
Basic weighted average shares outstanding (in shares)	153,309			146,051			151,459	143,938
Net income per share - Basic (USD per share)	$ 1.08			$ 0.94			$ 6.00	$ 5.33
Diluted Earnings Per Share
Income available to common shareholders	$ 165,477			$ 137,724			$ 908,389	$ 766,856
Effect of dilutive shares	0			0			0	0
Income available to common shareholders	$ 165,477			$ 137,724			$ 908,389	$ 766,856
Basic weighted average shares outstanding (in shares)	153,309			146,051			151,459	143,938
Dilutive shares (in shares)	87			16			38	60
Diluted weighted average shares outstanding (in shares)	153,396			146,067			151,497	143,998
Net income per share - Diluted (USD per share)	$ 1.08			$ 0.94			$ 6.00	$ 5.33