Restructuring (Schedule of Restructuring Costs) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019		Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Contract termination costs	$ 527	$ 1,918	[1]
Other costs	203	765
Total	730	2,683	[1]
Cumulative costs incurred to date	8,067	8,067		$ 5,384
Increases for incurred costs related to impairments of operating lease right-of-use assets		1,300
Contract termination costs [Member]
Restructuring Cost and Reserve [Line Items]
Cumulative costs incurred to date	6,094	6,094		4,176
Other costs [Member]
Restructuring Cost and Reserve [Line Items]
Cumulative costs incurred to date	$ 1,973	$ 1,973		$ 1,208

[1] Includes $1.3 million of operating lease ROU asset impairment costs.