Income Taxes - Operating loss carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating losses
Net operating loss carryforwards	$ 32	$ 24
State
Operating losses
Net operating loss carryforwards	12	9
Foreign
Operating losses
Net operating loss carryforwards	$ 20	$ 15

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant