Leases - Weighted Average Remaining Lease Term and Discount Rates (Details)	Sep. 30, 2020	Sep. 30, 2019
Offices
Weighted average remaining lease term (years)
Weighted average remaining lease term (years)	3 years 9 months 10 days	4 years 11 months 23 days
Weighted average discount rate
Weighted average discount rate	1.99%	2.65%
Data Centers
Weighted average remaining lease term (years)
Weighted average remaining lease term (years)	2 years 5 months 15 days	2 years 7 months 20 days
Weighted average discount rate
Weighted average discount rate	1.62%	1.82%

Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Name:	us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant