Employee Benefits, Net Periodic Benefit Costs (Details) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net Periodic Benefit Cost and Charges Relating to Other Benefit Plans
Deferred compensation plan	$ (0.3)	$ 0.2	$ (0.1)	$ 1.1
Defined contribution plans	1.2	1.1	5.9	5.5
Multiemployer pension plans	0.8	0.7	2.3	2.1
Total	(0.4)	2.4	1.6	10.0
VEBA [Member]
Net Periodic Benefit Cost and Charges Relating to Other Benefit Plans
Service cost	0.7	0.7	2.2	2.2
Interest cost	3.9	4.0	11.6	12.0
Expected return on plan assets	(7.6)	(5.2)	(22.8)	(15.7)
Amortization of prior service cost	1.1	1.0	3.1	3.1
Amortization of net gain	(0.2)	(0.1)	(0.6)	(0.3)
Total (income) cost relating to VEBAs	$ (2.1)	$ 0.4	$ (6.5)	$ 1.3

Defined benefit plan net periodic benefit cost and charges relating to other benefit plans.

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Defined Benefit Plan Net Periodic Benefit Cost and Charges Relating to Other Benefit Plans.

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The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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The amount of gains or losses recognized in net periodic benefit cost.

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The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

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An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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The amount of the cost recognized during the period for defined contribution plans.

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Amount of contributions made to multiemployer plans for each period for which a statement of income is presented. An employer may disclose total contributions to multiemployer plans without disaggregating the amounts attributable to pension plans and other postretirement benefit plans.

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