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Restructuring Charges (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Accruals for lease terminations			$ (377)	$ 6,453
Restructuring charges	$ 103	$ 13	(212)	6,524
Special termination benefits				6,200
Other Property Related Charges
Restructuring Cost and Reserve [Line Items]
Accruals for lease terminations			165
Severance Charges
Restructuring Cost and Reserve [Line Items]
Accruals for lease terminations			$ 0	6,453
Restructuring charges				$ 6,500