Restructuring Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Charges		$ 0	$ 0
2017 Strategic Restructuring Plan
Restructuring Reserve [Roll Forward]
Liability, beginning of period	$ 0
Charges	1,620,000
Non-cash activity	(41,000)
Liability end of period	1,579,000	0
2017 Strategic Restructuring Plan | Employee Separation Costs
Restructuring Reserve [Roll Forward]
Liability, beginning of period	0
Charges	1,515,000
Non-cash activity	7,000
Liability end of period	1,522,000	0
2017 Strategic Restructuring Plan | Asset-Related Charges
Restructuring Reserve [Roll Forward]
Liability, beginning of period	0
Charges	22,000
Non-cash activity	(22,000)
Liability end of period	0	0
2017 Strategic Restructuring Plan | Other
Restructuring Reserve [Roll Forward]
Liability, beginning of period	0
Charges	82,000
Non-cash activity	(25,000)
Liability end of period	$ 57,000	$ 0