For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 1		$ 1		$ 0
Revenue from Contract with Customer \| Customer Concentration Risk \| Four Largest Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk, percentage	41.00%	55.00%	44.00%	59.00%
Accounts Receivable \| Customer Concentration Risk \| Four Largest Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk, percentage			31.00%		40.00%