Shareholders' Equity - Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	140,896,598
Shareholders' equity, beginning balance	$ 9,419,091	$ 7,906,889
Net income	271,860	249,209
Other comprehensive income (loss)	22,218	(45,947)
Cash dividends	(104,552)	(90,411)
Public and other stock offerings	223,779	265,861
Stock-based compensation plans	$ 3,878	3,944
Common stock outstanding, ending balance (in shares)	143,155,761
Shareholders' equity, ending balance	$ 9,836,274	$ 8,289,545
Cash dividends (USD per share)	$ 0.74	$ 0.68
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	140,896,598	132,419,754
Shareholders' equity, beginning balance	$ 704	$ 662
Public and other stock offerings (in shares)	2,147,210	2,730,115
Public and other stock offerings	$ 11	$ 13
Stock-based compensation plans (in shares)	111,953	275,212
Stock-based compensation plans	$ 1	$ 2
Common stock outstanding, ending balance (in shares)	143,155,761	135,425,081
Shareholders' equity, ending balance	$ 716	$ 677
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	5,838,118	5,023,751
Public and other stock offerings	223,768	265,848
Stock-based compensation plans	3,877	3,942
Shareholders' equity, ending balance	6,065,763	5,293,541
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	369,112	69,803
Other comprehensive income (loss)	22,218	(45,947)
Shareholders' equity, ending balance	391,330	23,856
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	3,211,157	2,812,673
Net income	271,860	249,209
Cash dividends	(104,552)	(90,411)
Shareholders' equity, ending balance	$ 3,378,465	$ 2,971,471