Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Summary of cash paid for interest and income taxes

	Year Ended December 31,
(In thousands)	2017			2016		2015
Cash paid for interest and income taxes
Interest	$	79,846		$	86,723	$	92,749
Income taxes	40,626			688		7,550
Non-cash investing activities
Change in accrued capital costs	(3,516		)	7,168		(194,947		)