EMPLOYEE BENEFIT PLANS (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (net of tax)
Amortization of unrecognized (loss) gain	$ (4.8)	$ (3.9)	$ (2.1)
Prior service (credit) cost	4.6	5.7	7.0
Amortization of prior service cost	1.4	(0.3)	(0.2)
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	2.7	5.4	4.6
Interest cost	9.0	10.7	10.3
Expected return on plan assets	(10.7)	(11.1)	(9.7)
Amortization of net loss (gain)	7.0	4.0	3.5
Amortization of prior service cost	(2.3)	0.1	0.1
Net periodic benefit cost	5.7	9.1	8.8
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (net of tax)
Net loss (gain)	4.0	23.8	3.6
Amortization of unrecognized (loss) gain	(4.2)	(2.4)	(2.1)
Prior service (credit) cost		(15.1)
Amortization of prior service cost	1.4	(0.1)	(0.1)
Total recognized in other comprehensive income	1.2	6.2	1.4
Total recognized in net periodic benefit cost and other comprehensive income	6.9	15.3	10.2
Weighted Average Assumptions:
Discount rate (as a percent)	4.20%	4.80%	5.80%
Expected long-term rate of return plan assets (as a percent)	8.30%	8.30%	8.30%	8.50%
Rate of compensation increase (as a percent)	3.00%	4.00%	4.00%
Non-qualified Pension Plans
Total obligation	210.1	192.6	189.8
Expense associated with plans	5.7	9.1	8.8
Amounts recognized in accumulated other comprehensive income for net loss, net of tax	55.8	56.1
Amount recognized as prior service credit, net of tax	(13.4)	(14.8)
Estimated net loss and prior service credit, net of tax, that will be recognized in net periodic pension cost	42.4	41.3
Non-qualified Pension Plans
Components of Net Periodic Benefit Cost
Net periodic benefit cost	0.3	0.8	1.5
Non-qualified Pension Plans
Number of outside directors covered under the frozen non-qualified pension plan	2
Total obligation	7.9
Discount rate used to determine obligation (as a percent)	2.40%
Expense associated with plans	0.3	0.8	1.5
Amounts recognized in accumulated other comprehensive income for net loss, net of tax	2.0
Amount recognized as prior service credit, net of tax	0.9
Other Post-retirement Benefits
Components of Net Periodic Benefit Cost
Service cost	1.0	0.9	0.7
Interest cost	2.3	3.0	2.6
Amortization of net loss (gain)	0.6	1.9	0.4
Amortization of prior service cost	0.1	0.2	0.2
Net periodic benefit cost	4.0	6.0	3.9
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (net of tax)
Net loss (gain)	(0.4)	(2.5)	3.9
Amortization of unrecognized (loss) gain	(0.3)	(1.0)	(0.2)
Amortization of prior service cost		(0.1)	(0.1)
Total recognized in other comprehensive income	(0.7)	(3.6)	3.6
Total recognized in net periodic benefit cost and other comprehensive income	3.3	2.4	7.5
Weighted Average Assumptions:
Discount rate (as a percent)	4.30%	4.90%	5.80%
Rate of compensation increase (as a percent)	3.00%	4.00%	4.00%
Initial health care cost trend rate (as a percent)	8.00%	9.00%	10.00%
Ultimate rate (as a percent)	4.50%	5.00%	5.00%
Effect of one percentage point change in the assumed health care cost trend rates
Effect of one percentage point increase on total of service and interest cost components	0.6	0.6	0.5
Effect of one percentage point increase on post-retirement benefit obligation	6.5	6.6	7.1
Effect of one percentage point decrease on total of service and interest cost components	(0.4)	(0.5)	(0.4)
Effect of one percentage point decrease on post-retirement benefit obligation	(5.2)	(5.3)	(5.7)
Non-qualified Pension Plans
Total obligation	49.2	48.5	51.8
Expense associated with plans	4.0	6.0	3.9
Amounts recognized in accumulated other comprehensive income for net loss, net of tax	0.7	0.6
Amount recognized as prior service credit, net of tax	0.1	0.1
Estimated net loss and prior service credit, net of tax, that will be recognized in net periodic pension cost	$ 0.8	$ 0.7