Revenue Recognition - Narrative (Details)	6 Months Ended
	Jun. 30, 2020 cogeneration_facility utlity_company
Revenue from Contract with Customer [Abstract]
Payment term (within)	30 days
Number of cogeneration facilities selling majority of electric output not used in operations | cogeneration_facility	3
Number of utility companies under long term contract to buy electrical output | utlity_company	2