Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	$ 7,906,889	$ 6,791,203	$ 5,750,223
Other comprehensive income (loss) before reclassifications	296,333	122,826
Amounts reclassified from accumulated other comprehensive income	2,976	4,566
Net current-period other comprehensive income (loss)	299,309	127,392	56,994
Shareholders' equity, ending balance	9,419,091	7,906,889	6,791,203
Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	47	238
Other comprehensive income (loss) before reclassifications	(542)	(191)
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income (loss)	(542)	(191)
Shareholders' equity, ending balance	(495)	47	238
Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	69,756	(57,827)
Other comprehensive income (loss) before reclassifications	296,875	123,017
Amounts reclassified from accumulated other comprehensive income	2,976	4,566
Net current-period other comprehensive income (loss)	299,851	127,583
Shareholders' equity, ending balance	369,607	69,756	(57,827)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	69,803	(57,589)	(114,583)
Net current-period other comprehensive income (loss)	299,309	127,392	56,994
Shareholders' equity, ending balance	$ 369,112	$ 69,803	$ (57,589)