Transactions with Major Customers and Affiliates (Tables)

12 Months Ended

Dec. 31, 2019

Transactions with Major Customers and Affiliates [Abstract]

Schedule of revenue by major customers

During the periods presented, more than 10 percent of our operating revenues were generated from each of the following customers:

	Years Ended December 31,
	2019		2018		2017
	(Thousands of Dollars)
Puget Sound Energy, Inc.	$	121,792	$	115,238	$	120,226
Northwest Natural Gas Company	48,891		49,126		51,743
Cascade Natural Gas Corporation	46,969		46,164		48,071