Revenue from Contracts with Customers Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Adjustments to revenue for refunds or credits relating to prior periods	$ 0	$ 0	$ 0

Amount of cash outflow to customers for refund payments of revenue that was previously reported as deferred or unearned revenue.

No definition available.

Name:	us-gaap_DeferredRevenueRefundPayments1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration