Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Summary of Significant Accounting Policies Property, Plant, and Equipment (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	3.11%	3.18%	2.95%
Software \| Minimum
Property, plant, and equipment
Estimated useful life	5 years
Software \| Maximum
Property, plant, and equipment
Estimated useful life	15 years