Other Balance Sheet Items Other Balance Sheet Items (Narrative) (Details) $ in Millions	Sep. 30, 2023 USD ($)
Balance Sheet Related Disclosures [Abstract]
Tax Cuts and Jobs Act, Transition Tax for Accumulated Foreign Earnings, Liability	$ 19.3
Reston building purchase price	19.8
Reston building purchase price allocation - land	6.8
Reston building purchase price allocation - buildings	$ 13.0

Amount of tax liability from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Name:	us-gaap_TaxCutsAndJobsActOf2017TransitionTaxForAccumulatedForeignEarningsLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant