Financial Instruments Financial Instruments narrative (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Debt instrument fair value senior notes 2025	$ 563,600
Debt instrument fair value senior notes 2027	580,000
Debt instrument fair value senior notes 2031	763,500
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	$ 100

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

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