Segment Information Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting [Abstract]
Number of Reportable Segments			4	3
Revenue, Major Customer [Line Items]
Concentration risk, supplier			We currently buy a majority of our integrated circuit board assemblies from three suppliers. Management believes that other suppliers could provide similar products, but a change in suppliers, disputes with our suppliers, or unexpected constraints on the suppliers' production capacity could adversely affect operating results.
Revenue [Member] | Threshold for Reporting Customer Concentration [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	10.00%	10.00%	10.00%	10.00%
Revenue [Member] | Threshold for Reporting Customer Concentration [Member] | Gas Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage		10.00%		10.00%
Revenue [Member] | Threshold for Reporting Customer Concentration [Member] | Water Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	10.00%	10.00%	10.00%	10.00%
Revenue [Member] | Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	10.00%	11.00%
Revenue [Member] | Customer A [Member] | Electricity Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	23.00%	22.00%	22.00%	20.00%
Revenue [Member] | Customer A [Member] | Gas Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	12.00%		12.00%
Revenue [Member] | Customer A [Member] | Networks Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	18.00%		13.00%
Revenue [Member] | Customer B [Member] | Electricity Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	16.00%		16.00%
Revenue [Member] | Customer B [Member] | Networks Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage	15.00%		13.00%