Transactions with Major Customers and Affiliates (Tables)

12 Months Ended

Dec. 31, 2014

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,
	2014		2013		2012
	(Thousands of Dollars)
Puget Sound Energy, Inc.	$	113,398	$	110,111	$	100,799
Northwest Natural Gas Company	50,631		51,085		42,297