Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan Assets
Expected contributions to the defined benefit pension plan in 2019	$ 4.6
Net actuarial loss	57.6	$ 58.7
Expense provision for 401 (k) plans	4.2	4.2	$ 4.0
Hedge Funds Investments [Member]
Pension Plan Assets
Investments in hedge funds which do not have readily determinable fair values	16.5	30.7
Employee Pension Plans [Member]
Pension Plan Assets
Other comprehensive gain (loss)	1.1	$ 2.4	$ 4.3
Amount to be amortized from other comprehensive loss into cost in 2019	$ 1.9
Discount rate (as a percent)	4.10%	3.50%
Expected return on assets (as a percent)	6.00%	6.00%	6.00%
Other Multiemployer Pension Plans
Pension Plan Assets
Multiemployer Plan, Period Contributions	$ 29.3	$ 27.8	$ 48.3

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount, before tax, after reclassification adjustment, of increase (decrease) in accumulated other comprehensive income from gain (loss) of defined benefit plan.

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Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

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Amount of cost (credit) included in accumulated other comprehensive (income) loss expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

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