Statement Of Cash Flow Information - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Interest paid, net of interest capitalized	$ 7,369	$ 10,367	$ 18,749
Income taxes paid	$ 5,705	$ 6,015	$ 5,635