Shareholders' Equity - Schedule of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	$ 6,791,203	$ 5,750,223
Other comprehensive income (loss) before reclassifications	58,979	(1)
Amounts reclassified from accumulated other comprehensive income	1,142	1,053
Net current-period other comprehensive income (loss)	60,121	1,052
Shareholders' equity, ending balance	7,213,156	6,127,775
Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	238	132
Other comprehensive income (loss) before reclassifications	(63)	(1)
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income (loss)	(63)	(1)
Shareholders' equity, ending balance	175	131
Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	(57,827)	(114,715)
Other comprehensive income (loss) before reclassifications	59,042	0
Amounts reclassified from accumulated other comprehensive income	1,142	1,053
Net current-period other comprehensive income (loss)	60,184	1,053
Shareholders' equity, ending balance	2,357	(113,662)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	(57,589)	(114,583)
Net current-period other comprehensive income (loss)	60,121	1,052
Shareholders' equity, ending balance	$ 2,532	$ (113,531)