Property And Equipment (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property And Equipment [Abstract]
Depreciation expense for operating property	$ 14,000,000	$ 15,100,000	$ 13,600,000
Capitalized interest charges	$ 1,200,000	$ 297,000