Statement Of Cash Flow Information - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Interest paid, net of interest capitalized	$ 18,749	$ 14,555	$ 11,628
Income taxes paid	$ 5,635	$ 16,905	$ 70,509