Significant Accounting Policies Trade Receivables and Allowance for Doubtful Accounts (Details) $ in Millions	Dec. 31, 2020 USD ($) d	Dec. 31, 2019 USD ($)
Significant Accounting Policies [Abstract]
Customer credit terms (in days) | d	30
Allowance for Doubtful Accounts Receivable, Current | $	$ 1.1	$ 1.1