Investment in TiO2 Manufacturing Joint Venture and Other Assets - Summary of Financial Information (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Information [Line Items]
Current assets	$ 1,262.2				$ 837.4				$ 1,262.2	$ 837.4
Property and equipment, net	588.7				516.0				588.7	516.0	$ 515.6
Total assets	2,907.5				2,443.2				2,907.5	2,443.2	2,537.4
Other liabilities, primarily current	33.4				23.3				33.4	23.3
Total liabilities and equity	2,907.5				2,443.2				2,907.5	2,443.2
Net sales	495.9	$ 496.5	$ 481.7	$ 405.3	390.5	$ 393.1	$ 387.5	$ 348.3	1,879.4	1,519.4	1,487.9
Cost of sales									1,277.4	1,219.2	1,259.5
General and administrative									269.4	236.4	248.6
Total costs and expenses									1,612.8	1,518.8	1,561.7
Net income (loss)									302.6	(3.0)	(171.1)
LPC
Financial Information [Line Items]
Current assets	104.1				94.5				104.1	94.5
Property and equipment, net	116.1				111.6				116.1	111.6
Total assets	220.2				206.1				220.2	206.1
Other liabilities, primarily current	44.4				45.2				44.4	45.2
Partners’ equity	175.8				160.9				175.8	160.9
Total liabilities and equity	$ 220.2				$ 206.1				220.2	206.1
Net sales									315.8	315.4	339.0
Cost of sales									315.4	314.9	338.5
General and administrative									0.4	0.5	0.5
Total costs and expenses									315.8	315.4	339.0
Net income (loss)									0.0	0.0	0.0
LPC | Kronos Worldwide, Inc.
Financial Information [Line Items]
Net sales									157.5	157.5	176.5
Venator Materials PLC | Tioxide Group | Huntsman P&A Investments LLC
Financial Information [Line Items]
Net sales									$ 158.3	$ 157.9	$ 162.5