Segment Results Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 $ / shares	Sep. 30, 2016 $ / shares	Sep. 30, 2017 USD ($) $ / shares	Sep. 30, 2016 $ / shares
Segment Reporting [Abstract]
Number of Reportable Segments	3	3	3	3
Segment Reporting Information [Line Items]
Concentration Risk, Supplier			We currently buy a majority of our integrated circuit boards, an important component in our products, from two suppliers. Management believes that other suppliers could provide similar circuit boards, but a change in suppliers, disputes with our suppliers, or unexpected constraints on the suppliers’ production capacity could adversely affect operating results.
Unusual or Infrequent Item, or Both, Insurance Proceeds | $			$ 8.0
Earnings (loss) per common share - Basic	$ 0.66	$ (0.26)	$ 1.44	$ 0.53
Earnings (loss) per common share - Diluted	$ 0.65	$ (0.26)	$ 1.41	$ 0.52
Gross Profit [Member]
Segment Reporting Information [Line Items]
Unusual or Infrequent Item, or Both, Insurance Proceeds | $			$ 8.0
Water Operating Segment [Member] | Insurance Recovery, net of tax [Member]
Segment Reporting Information [Line Items]
Earnings (loss) per common share - Basic			$ 0.13
Earnings (loss) per common share - Diluted			$ 0.12