FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS: (Details) In Millions, unless otherwise specified	3 Months Ended		1 Months Ended							3 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2013 USD ($) item	Dec. 31, 2012 USD ($)	Mar. 31, 2013 Interest rate swaps Titanium Dioxide Pigments venture facility agreement Sachtleben GmbH USD ($)	Mar. 31, 2013 Interest rate swaps Titanium Dioxide Pigments venture facility agreement Sachtleben GmbH EUR (€)	Mar. 31, 2013 Derivatives Designated as Hedging Instruments: USD ($)	Mar. 31, 2013 Derivatives Designated as Hedging Instruments: Foreign exchange contracts Accrued expenses and other current liabilities USD ($)	Dec. 31, 2012 Derivatives Not Designated as Hedging Instruments: USD ($)	Mar. 31, 2013 Derivatives Not Designated as Hedging Instruments: Interest rate swaps USD ($)	Dec. 31, 2012 Derivatives Not Designated as Hedging Instruments: Interest rate swaps USD ($)	Mar. 31, 2013 Derivatives Not Designated as Hedging Instruments: Interest rate swaps Titanium Dioxide Pigments joint venture	Jul. 31, 2012 Derivatives Not Designated as Hedging Instruments: Interest rate swaps Titanium Dioxide Pigments joint venture EUR (€)	Mar. 31, 2013 Derivatives Not Designated as Hedging Instruments: Interest rate swaps Subject to Libor floor USD ($)	Dec. 31, 2012 Derivatives Not Designated as Hedging Instruments: Interest rate swaps Subject to Libor floor USD ($)	Dec. 31, 2012 Derivatives Not Designated as Hedging Instruments: Interest rate swaps Accrued expenses and other current liabilities USD ($)	Dec. 31, 2012 Derivatives Not Designated as Hedging Instruments: Interest rate swaps Other liabilities USD ($)
Derivatives
Percentage of outstanding term loan facility to be hedged										50.00%
Period of hedging for outstanding term loan facility										2 years
Variable rate debt outstanding								$ 911.0	$ 924.1			$ 587.3	$ 587.3
Interest rate, description												Libor	Libor
Interest rate, description floor rate (as a percent)												1.00%	1.00%
Payment on termination/ settlement of derivatives			3.9	3.0
Notional amount						12.6					400.0			662.9
Liability Derivatives, Fair Value					0.1	0.1	4.8							3.0	1.8
Total derivatives	$ 0.1	$ 4.8
Number of counterparties who have experienced a significant downgrade	0