Long-Lived Asset Impairment Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long lived assets held and used	$ 1,028	$ 12,264
Long lived assets held for sale	4,023	14,290
Total nonrecurring for value measurements	5,051	26,554
Carrying value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long lived assets held and used	815	7,110
Long lived assets held for sale	11,202	14,761
Total nonrecurring for value measurements	12,017	21,871
Quoted prices in active markets for identical assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long lived assets held and used
Long lived assets held for sale
Total nonrecurring for value measurements
Significant other observable inputs (Level 2 )
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long lived assets held and used		7,110
Long lived assets held for sale		14,761
Total nonrecurring for value measurements		21,871
Significant unobservable inputs (Level 3 ) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long lived assets held and used	815
Long lived assets held for sale	11,202
Total nonrecurring for value measurements	$ 12,017