Revenue (Narrative - Performance Obligations) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Remaining performance obligation amount	$ 1,274,218	$ 1,454,406
Material Rights [Member]
Remaining performance obligation amount	$ 464,296	$ 465,668

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Name:	us-gaap_RevenueRemainingPerformanceObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant