Accounting Policies - Derivative Instruments (Details) - Convertible Subordinated Debt - Convertible Senior Notes at 5.00% February 2021 - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2016
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,250,000	$ 1,250,000	$ 150,000,000
Interest rate (as a percent)	5.00%

Face (par) amount of debt instrument at time of issuance.

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