Shareholders' Equity - Schedule of Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2025	Mar. 31, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)		155,258,845			155,258,845
Shareholders' equity, beginning balance	$ 12,780,481	$ 12,157,669	$ 11,273,209	$ 10,870,064	$ 12,157,669	$ 10,870,064
Net income	485,576	351,858	432,023	311,292	837,434	743,315
Other comprehensive income (loss)	(5,587)	16,423	27,108	(49,936)	$ 10,836	(22,828)
Cash dividends	(138,416)	(135,453)	(121,667)	(119,898)
Public and other stock offerings	3,841	383,537	4,025	257,768
Stock-based compensation plans	$ 12,070	6,447	3,941	3,919
Common stock outstanding, ending balance (in shares)	158,835,123				158,835,123
Shareholders' equity, ending balance	$ 13,137,965	$ 12,780,481	$ 11,618,639	$ 11,273,209	$ 13,137,965	$ 11,618,639
Cash dividends per share (USD per share)	$ 0.870	$ 0.87	$ 0.805	$ 0.805	$ 1.74	$ 1.61
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	158,726,065	155,258,845	150,834,397	148,492,783	155,258,845	148,492,783
Shareholders' equity, beginning balance	$ 794	$ 776	$ 754	$ 742	$ 776	$ 742
Public and other stock offerings (in shares)	26,367	3,329,358	34,687	2,177,864
Public and other stock offerings		$ 17		$ 11
Stock-based compensation plans (in shares)	82,691	137,862	5,468	163,750
Stock-based compensation plans		$ 1		$ 1
Common stock outstanding, ending balance (in shares)	158,835,123	158,726,065	150,874,552	150,834,397	158,835,123	150,874,552
Shareholders' equity, ending balance	$ 794	$ 794	$ 754	$ 754	$ 794	$ 754
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	7,864,525	7,474,559	6,945,795	6,684,120	7,474,559	6,684,120
Public and other stock offerings	3,841	383,520	4,025	257,757
Stock-based compensation plans	12,070	6,446	3,941	3,918
Shareholders' equity, ending balance	7,880,436	7,864,525	6,953,761	6,945,795	7,880,436	6,953,761
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	482,138	465,715	468,592	518,528	465,715	518,528
Other comprehensive income (loss)	(5,587)	16,423	27,108	(49,936)
Shareholders' equity, ending balance	476,551	482,138	495,700	468,592	476,551	495,700
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	4,433,024	4,216,619	3,858,068	3,666,674	4,216,619	3,666,674
Net income	485,576	351,858	432,023	311,292
Cash dividends	(138,416)	(135,453)	(121,667)	(119,898)
Shareholders' equity, ending balance	$ 4,780,184	$ 4,433,024	$ 4,168,424	$ 3,858,068	$ 4,780,184	$ 4,168,424