Related Party Transactions (Tables)

6 Months Ended

Jun. 30, 2017

Related Party Transactions [Abstract]

Schedule of Related Party Transactions [Table Text Block]

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2017		2016		2017		2016
	(In thousands)
Operating and maintenance expenses	$	17,933	$	15,667	$	35,439	$	31,633
Selling, general and administrative expenses	3,063		2,346		6,081		4,461
Total charges	$	20,996	$	18,013	$	41,520	$	36,094