Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Fair Value Measurements - Summary of Carrying Value and Estimated Fair Value of all Debt (Parenthetical) (Details)	Sep. 30, 2021	Jul. 01, 2021	Jun. 30, 2021	May 31, 2021	Sep. 30, 2020	Aug. 31, 2017
3.75% Convertible Notes Due 2022
Fair value measurement
Interest rate (as a percent)	3.75%		3.75%	3.75%	3.75%	3.75%
3.75% Convertible Notes Due 2026
Fair value measurement
Interest rate (as a percent)	3.75%	3.75%	3.75%	3.75%