Shareholders' Equity - Schedule of Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	161,568,384
Shareholders' equity, beginning balance	$ 13,558,890	$ 12,157,669
Net income	402,964	351,858
Other comprehensive income (loss)	(4,805)	16,423
Cash dividends	(160,407)	(135,453)
Public and other stock offerings	474,643	383,537
Stock-based compensation plans	$ 11,607	6,447
Common stock outstanding, ending balance (in shares)	165,434,477
Shareholders' equity, ending balance	$ 14,282,892	$ 12,780,481
Cash dividends per share (USD per share)	$ 1.00	$ 0.87
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	161,568,384	155,258,845
Shareholders' equity, beginning balance	$ 808	$ 776
Public and other stock offerings (in shares)	3,709,647	3,329,358
Public and other stock offerings	$ 18	$ 17
Stock-based compensation plans (in shares)	156,446	137,862
Stock-based compensation plans	$ 1	$ 1
Common stock outstanding, ending balance (in shares)	165,434,477	158,726,065
Shareholders' equity, ending balance	$ 827	$ 794
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	8,221,455	7,474,559
Public and other stock offerings	474,625	383,520
Stock-based compensation plans	11,606	6,446
Shareholders' equity, ending balance	8,707,686	7,864,525
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	475,015	465,715
Other comprehensive income (loss)	(4,805)	16,423
Shareholders' equity, ending balance	470,210	482,138
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	4,861,612	4,216,619
Net income	402,964	351,858
Cash dividends	(160,407)	(135,453)
Shareholders' equity, ending balance	$ 5,104,169	$ 4,433,024