STOCK-BASED COMPENSATION PLANS: (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options
Assumptions used in valuation
Risk-free interest rate (as a percent)		1.80%
Expected life		5 years
Expected volatility (as a percent)		47.60%
Annual dividend yield (as a percent)		2.30%
Stock Grants and SARs
Compensation expense	$ 1.1	$ 1.5
Stock Grants [Member] | Non Employee Director [Member]
Stock Grants and SARs
Granted (in shares)		12,000	31,250	25,000
Compensation expense		0.4	0.8	0.2
SARs
Assumptions used in valuation
Risk-free interest rate (as a percent)		1.50%	0.90%	0.90%
Expected life		5 years	5 years	5 years
Expected volatility (as a percent)		65.00%	73.00%	73.00%
Annual dividend yield (as a percent)		2.20%	4.30%	5.20%
Stock Grants and SARs
Aggregate intrinsic value	19.6	19.6
Weighted average remaining contractual life		6 years 10 months 21 days
Stock Grants and SARs
Outstanding at the beginning of the year (in shares)		1,400,000
Granted (in shares)		200,000
Outstanding at the end of the year (in shares)	1,600,000	1,600,000	1,400,000
Weighted-Average Price
Outstanding at the beginning of the year (in dollars per share)		$ 13.25
Granted (in dollars per share)		$ 27.86
Outstanding at the end of the year (in dollars per share)	$ 15.08	$ 15.08	$ 13.25
Subsidiary Stock Awards
Stock Grants and SARs
Compensation expense		0.2	0.3	0.7
LTIP | SARs | President and Chief Executive Officer
STOCK-BASED COMPENSATION PLANS:
Base value of rights granted (in dollars per share)	$ 27.86	$ 27.86	$ 14.21	$ 11.68
Term of rights		10 years
Stock Grants and SARs
Compensation expense		$ 2.6	$ 3.2	$ 2.0
Stock Grants and SARs
Granted (in shares)		200,000	500,000	400,000