Shareholders' Equity - Forward Sales Agreement (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares
Class of Stock [Line Items]
Shares Available (in shares) | shares	5,146,620
Net Proceeds Available | $	$ 547,222
September 30, 2020
Class of Stock [Line Items]
Shares Available (in shares) | shares	1,662,270
Net Proceeds Available | $	$ 174,142
Forward Price (dollars per share) | $ / shares	$ 104.76
March 31, 2021
Class of Stock [Line Items]
Shares Available (in shares) | shares	2,089,927
Net Proceeds Available | $	$ 229,650
Forward Price (dollars per share) | $ / shares	$ 109.88
June 30, 2021
Class of Stock [Line Items]
Shares Available (in shares) | shares	1,394,423
Net Proceeds Available | $	$ 143,430
Forward Price (dollars per share) | $ / shares	$ 102.86