Pension Plan and Postretirement Benefits Other Than Pension - Pension plan asset allocation (Details)	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets allocation	100.00%	100.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets allocation	51.00%	2.00%
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets allocation	49.00%	98.00%

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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