SEGMENT AND GEOGRAPHIC INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information
Net sales	$ 355,340	$ 343,970	$ 646,055	$ 639,600
Operating income/(loss)	43,691	40,474	55,812	63,174
Total assets	1,269,663		1,269,663		$ 1,182,365
Segment Change
Segment Reporting Information
Net sales		1,000		1,800
Operating income/(loss)		100		200
Operating Segments | Water Systems
Segment Reporting Information
Net sales	205,000	211,400	393,400	404,000
Operating income/(loss)	30,900	32,200	50,100	57,300
Total assets	707,500		707,500		679,700
Operating Segments | Distribution
Segment Reporting Information
Net sales	87,100	79,500	140,400	135,700
Operating income/(loss)	4,500	4,000	200	3,200
Total assets	204,900		204,900		165,100
Operating Segments | Fueling Systems
Segment Reporting Information
Net sales	78,000	73,100	138,300	131,700
Operating income/(loss)	21,700	19,000	34,000	32,700
Total assets	299,600		299,600		275,700
Operating Segments | Corporate And Eliminations
Segment Reporting Information
Total assets	57,700		57,700		$ 61,900
Intersegment Sales | Distribution
Segment Reporting Information
Net sales	0	0	0	0
Intersegment Sales | Fueling Systems
Segment Reporting Information
Net sales	0	0	0	0
Corporate And Eliminations
Segment Reporting Information
Net sales	(14,800)	(20,000)	(26,000)	(31,800)
Operating income/(loss)	(13,400)	(14,700)	(28,500)	(30,000)
United States & Canada | Water Systems
Segment Reporting Information
Net sales	103,100	98,300	189,900	183,000
United States & Canada | Distribution
Segment Reporting Information
Net sales	87,100	79,500	140,400	135,700
United States & Canada | Fueling Systems
Segment Reporting Information
Net sales	45,900	37,500	81,100	69,500
United States & Canada | Intersegment Sales | Water Systems
Segment Reporting Information
Net sales	14,800	20,000	26,000	31,800
Latin America | Water Systems
Segment Reporting Information
Net sales	29,400	28,900	59,900	58,000
EMEA | Water Systems
Segment Reporting Information
Net sales	39,000	45,200	76,700	91,400
EMEA | Segment Change
Segment Reporting Information
Net sales		3,500		6,600
Asia Pacific | Water Systems
Segment Reporting Information
Net sales	18,700	19,000	40,900	39,800
All Other | Fueling Systems
Segment Reporting Information
Net sales	$ 32,100	$ 35,600	$ 57,200	$ 62,200