Employee Benefit Plans - Expected long-term return by asset category (Details)	12 Months Ended
Dec. 31, 2020
Growth assets
Expected Long Term Return [Abstract]
Expected long-term return	6.90%
Asset allocation [Abstract]
Asset allocation	68.00%
Hedging assets
Expected Long Term Return [Abstract]
Expected long-term return	0.70%
Asset allocation [Abstract]
Asset allocation	30.00%
Cash
Expected Long Term Return [Abstract]
Expected long-term return	0.10%
Asset allocation [Abstract]
Asset allocation	2.00%

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2919-114920

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration