Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan Assets
Expected contributions to the defined benefit pension plan in 2020	$ 4.1
Net actuarial loss	56.5	$ 57.6
Expense provision for 401 (k) plans	4.1	4.2	$ 4.2
Hedge Funds Investments [Member]
Pension Plan Assets
Investments in hedge funds which do not have readily determinable fair values	13.5	16.5
Employee Pension Plans [Member]
Pension Plan Assets
Other comprehensive gain (loss)	1.2	$ 1.1	$ 2.4
Amount to be amortized from other comprehensive loss into cost in 2020	$ 2.4
Discount rate (as a percent)	3.10%	4.10%
Expected return on assets (as a percent)	5.75%	6.00%	6.00%
Other Multiemployer Pension Plans
Pension Plan Assets
Multiemployer Plan, Period Contributions	$ 31.4	$ 29.3	$ 27.8