Restructuring Activities and Other Charges - Schedule of Restructuring Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Balance at December 31	$ 1,566	$ 359
Expenses	0	5,615	$ 1,053
Cash payments	(1,082)	(4,408)
Balance at December 31	484	1,566	359
Employee Severance and Related Benefits
Restructuring Reserve [Roll Forward]
Balance at December 31	1,349	284
Expenses	0	4,552
Cash payments	(866)	(3,487)
Balance at December 31	484	1,349	284
Lease and Contract Termination Costs
Restructuring Reserve [Roll Forward]
Balance at December 31	17	75
Expenses	0	863
Cash payments	(17)	(921)
Balance at December 31	0	17	75
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Balance at December 31	200	0
Expenses	0	200
Cash payments	(200)	0
Balance at December 31	$ 0	$ 200	$ 0