Commitments and Contingencies Note Receivable Details (Details)	3 Months Ended	9 Months Ended	14 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Oct. 31, 2016 defendant
Other Commitments [Line Items]
Other gain from continuing operations	$ 5,500,000
Litigation Settlement, amount awarded from other party	500,000
Increase (Decrease) in notes receivable, current	800,000
Increase (Decrease) in notes receivables, noncurrent	3,800,000
Houston Police Department, Environmental Enforcement | Pending Litigation
Other Commitments [Line Items]
Loss contingency, number of defendants | defendant			2
Loss contingency, estimate of possible loss	$ 250,000	$ 250,000
Plea bargain declined		$ 7,500