New Accounting Standards - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Oct. 01, 2019	Sep. 30, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Oct. 01, 2019
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect	false
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member	us-gaap:AccountingStandardsUpdate201409Member
Operating lease liability	$ 358,119
Right-of-use operating lease assets	341,533			$ 0
Build-to-suit liability	$ 0			$ 90,292
Accounting Standards Update 2016-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease liability			$ 366,800
Right-of-use operating lease assets			359,200
Build-to-suit asset			90,300
Build-to-suit liability			$ 90,300