Pension Plans and Other Postretirement Benefits Current Forecast of Benefit Payments which Reflect Expected Future Service (Detail) (Rockwood Holdings, Inc., USD $) In Millions, unless otherwise specified	Mar. 31, 2015
United States Pension Plan of US Entity
Defined Benefit Plan Disclosure [Line Items]
Remainder of 2015	$ 1.4
2016	1.6
2017	1.7
2018	1.9
2019	2.0
2020-2024	11.1
Foreign Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Remainder of 2015	12.0
2016	16.4
2017	16.0
2018	16.8
2019	16.9
2020-2024	$ 89.8