RESTRUCTURING AND OTHER SEVERANCE COSTS: (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012
Restructuring and other severance costs
Restructuring charges expensed	$ 5.7	$ 13.2
Other severance-related costs	1.4	1.0
Total	7.1	14.2
Restructuring reserve
Balance at beginning of period	11.7
Restructuring charge	5.7
Utilized	(4.1)
Foreign exchange and other	(0.3)
Balance at end of period	13.0
Reporting Segments, Created	2
Assets write-down
Restructuring and other severance costs
Restructuring charges expensed		11.3
Lithium
Restructuring and other severance costs
Total	3.9	11.3
Restructuring reserve
Trade name wrote-off	10.3
Surface Treatment
Restructuring and other severance costs
Total	2.2	0.8
Performance Additives
Restructuring and other severance costs
Total	0.6	2.0
Severance/Relocation
Restructuring and other severance costs
Restructuring charges expensed	1.2	0.6
Restructuring reserve
Balance at beginning of period	9.8
Restructuring charge	1.2
Utilized	(2.9)
Foreign exchange and other	(0.2)
Balance at end of period	7.9
Total charges	12.2
Incurred to date	(11.1)
Expected future costs	1.1
Severance/Relocation | Lithium
Restructuring reserve
Total charges	3.8
Incurred to date	(3.6)
Expected future costs	0.2
Severance/Relocation | Surface Treatment
Restructuring reserve
Total charges	4.7
Incurred to date	(4.4)
Expected future costs	0.3
Severance/Relocation | Performance Additives
Restructuring reserve
Total charges	3.7
Incurred to date	(3.1)
Expected future costs	0.6
Facility Closure
Restructuring and other severance costs
Restructuring charges expensed	4.5	1.3
Restructuring reserve
Balance at beginning of period	1.9
Restructuring charge	4.5
Utilized	(1.2)
Foreign exchange and other	(0.1)
Balance at end of period	5.1
Total charges	44.9
Incurred to date	(37.5)
Expected future costs	7.4
Facility Closure | Lithium
Restructuring reserve
Total charges	31.6
Incurred to date	(30.1)
Expected future costs	1.5
Fixed asset write-downs	12.0
Facility Closure | Surface Treatment
Restructuring reserve
Total charges	7.4
Incurred to date	(5.7)
Expected future costs	1.7
Facility Closure | Performance Additives
Restructuring reserve
Total charges	5.9
Incurred to date	(1.7)
Expected future costs	$ 4.2