Segment Reporting - Segment Reporting (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net sales	$ 358.1	$ 326.3	$ 718.8	$ 620.6
Gross profit	102.8	105.1	207.3	196.0
Loss on disposal of subsidiary	0.0	(1.0)	0.0	(1.0)
Foreign exchange loss on liquidation of subsidiary	0.0	0.0	0.0	(1.8)
Operating income/(loss)	28.3	33.5	57.2	58.8
Operating Segments [Member] \| Fuel Specialties [Member]
Segment Reporting Information [Line Items]
Net sales	134.2	121.3	277.6	247.7
Gross profit	44.5	45.2	93.0	91.3
Operating income/(loss)	23.7	23.9	51.9	50.9
Operating Segments [Member] \| Fuel Specialties [Member] \| Refinery and Performance [Member]
Segment Reporting Information [Line Items]
Net sales	98.1	88.7	209.1	189.1
Operating Segments [Member] \| Fuel Specialties [Member] \| Other [Member]
Segment Reporting Information [Line Items]
Net sales	36.1	32.6	68.5	58.6
Operating Segments [Member] \| Performance Chemicals [Member]
Segment Reporting Information [Line Items]
Net sales	118.9	104.9	242.9	199.4
Gross profit	23.8	17.4	49.2	34.1
Operating income/(loss)	9.7	6.5	21.8	12.5
Operating Segments [Member] \| Performance Chemicals [Member] \| Personal Care [Member]
Segment Reporting Information [Line Items]
Net sales	62.6	48.6	123.0	96.1
Operating Segments [Member] \| Performance Chemicals [Member] \| Home Care [Member]
Segment Reporting Information [Line Items]
Net sales	26.5	29.4	56.2	56.3
Operating Segments [Member] \| Performance Chemicals [Member] \| Other [Member]
Segment Reporting Information [Line Items]
Net sales	29.8	26.9	63.7	47.0
Operating Segments [Member] \| Oilfield Services [Member]
Segment Reporting Information [Line Items]
Net sales	95.0	76.1	187.9	142.6
Gross profit	28.6	29.0	60.0	54.4
Operating income/(loss)	4.1	3.7	7.1	6.7
Operating Segments [Member] \| Octane Additives [Member]
Segment Reporting Information [Line Items]
Net sales	10.0	24.0	10.4	30.9
Gross profit	5.9	13.5	5.1	16.2
Operating income/(loss)	5.2	12.8	3.8	14.8
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Corporate costs	$ (14.4)	$ (12.4)	$ (27.4)	$ (23.3)

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