Income Taxes - Components of Comprehensive Provision for Income Taxes Allocation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Income Tax [Line Items]
United States	$ (44.7)	$ (35.3)	$ 40.1
Non-U.S. subsidiaries	47.7	(38.5)	71.9
Income (loss) before income taxes	3.0	(73.8)	112.0
Expected tax expense (benefit) at U.S. federal statutory income tax rate of 35%	1.1	(25.8)	39.2
Non-U.S. tax rates	(4.3)	0.6	(4.1)
Incremental net tax (benefit) on earnings and losses of non-U.S. and non-tax group companies	8.2	(37.6)	(2.2)
Valuation allowance	(2.2)	159.0
U.S. state income taxes, net	(0.1)	(1.3)	4.1
Adjustment to the reserve for uncertain tax positions, net	7.2	0.8	(3.7)
Nondeductible expenses	2.2	3.0	2.8
Domestic production activities deduction	(2.1)	(0.6)	(0.9)
Other, net	(0.6)	(0.8)	(2.7)
Provision for income taxes (benefit)	6.0	97.3	32.5
Comprehensive provision for income taxes (benefit) allocable to:
Net income (loss)	6.0	97.3	32.5
Other comprehensive income (loss):
Marketable securities	2.1	(4.1)	(11.3)
Currency translation	(3.4)	(17.3)	(16.9)
Interest rate swap	0.2	(1.7)
Total	(0.6)	77.9	(30.1)
Pension Plans
Other comprehensive income (loss):
Defined benefit plans	(5.0)	4.1	(33.2)
OPEB Plans
Other comprehensive income (loss):
Defined benefit plans	(0.5)	$ (0.4)	$ (1.2)
Kronos Worldwide, Inc. | US-Canada APA
Schedule Of Income Tax [Line Items]
U.S. – Canada APA	$ (3.4)