Shareholders' Equity - Schedule of Components of Equity (Details) - USD ($) $ / shares in Units, $ 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)			148,492,783				148,492,783
Shareholders' equity, beginning balance	$ 11,618,639	$ 11,273,209	$ 10,870,064	$ 10,205,205	$ 9,836,274	$ 9,419,091	$ 10,870,064	$ 9,419,091
Net income	165,564	432,023	311,292	137,807	357,671	271,860	908,879	767,338
Other comprehensive income (loss)	14,432	27,108	(49,936)	43,406	(30,333)	22,218	$ (8,396)	35,291
Cash dividends	(125,154)	(121,667)	(119,898)	(108,349)	(106,173)	(104,552)
Public and other stock offerings	499,584	4,025	257,768	315,697	143,814	223,779
Stock-based compensation plans	$ 10,011	3,941	3,919	8,615	3,952	3,878
Common stock outstanding, ending balance (in shares)	155,229,024						155,229,024
Shareholders' equity, ending balance	$ 12,183,076	$ 11,618,639	$ 11,273,209	$ 10,602,381	$ 10,205,205	$ 9,836,274	$ 12,183,076	$ 10,602,381
Cash dividends per share (USD per share)	$ 0.805	$ 0.805	$ 0.805	$ 0.740	$ 0.74	$ 0.74	$ 2.415	$ 2.220
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	150,874,552	150,834,397	148,492,783	144,484,650	143,155,761	140,896,598	148,492,783	140,896,598
Shareholders' equity, beginning balance	$ 754	$ 754	$ 742	$ 722	$ 716	$ 704	$ 742	$ 704
Public and other stock offerings (in shares)	4,288,217	34,687	2,177,864	2,754,533	1,316,930	2,147,210
Public and other stock offerings	$ 22		$ 11	$ 15	$ 6	$ 11
Stock-based compensation plans (in shares)	66,255	5,468	163,750	65,355	11,959	111,953
Stock-based compensation plans			$ 1			$ 1
Common stock outstanding, ending balance (in shares)	155,229,024	150,874,552	150,834,397	147,304,538	144,484,650	143,155,761	155,229,024	147,304,538
Shareholders' equity, ending balance	$ 776	$ 754	$ 754	$ 737	$ 722	$ 716	$ 776	$ 737
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	6,953,761	6,945,795	6,684,120	6,213,523	6,065,763	5,838,118	6,684,120	5,838,118
Public and other stock offerings	499,562	4,025	257,757	315,682	143,808	223,768
Stock-based compensation plans	10,011	3,941	3,918	8,615	3,952	3,877
Shareholders' equity, ending balance	7,463,334	6,953,761	6,945,795	6,537,820	6,213,523	6,065,763	7,463,334	6,537,820
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	495,700	468,592	518,528	360,997	391,330	369,112	518,528	369,112
Other comprehensive income (loss)	14,432	27,108	(49,936)	43,406	(30,333)	22,218
Shareholders' equity, ending balance	510,132	495,700	468,592	404,403	360,997	391,330	510,132	404,403
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	4,168,424	3,858,068	3,666,674	3,629,963	3,378,465	3,211,157	3,666,674	3,211,157
Net income	165,564	432,023	311,292	137,807	357,671	271,860
Cash dividends	(125,154)	(121,667)	(119,898)	(108,349)	(106,173)	(104,552)
Shareholders' equity, ending balance	$ 4,208,834	$ 4,168,424	$ 3,858,068	$ 3,659,421	$ 3,629,963	$ 3,378,465	$ 4,208,834	$ 3,659,421