Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan Assets
Expected contributions to the defined benefit pension plan in 2017	$ 2.6
Expense provision for 401 (k) plans	4.0	$ 4.0	$ 3.6
Hedge Fund Investments [Member]
Pension Plan Assets
Investments in hedge funds which do not have readily determinable fair values	39.1	52.1
Employee Pension Plans [Member]
Pension Plan Assets
Other comprehensive gain (loss)	4.3	$ 0.7	$ 13.9
Amount to be amortized from other comprehensive loss into cost in 2017	$ 1.8
Discount rate (as a percent)	3.90%	4.10%
Expected return on assets (as a percent)	6.00%	6.50%	6.75%
Other Multiemployer Pension Plans [Member]
Pension Plan Assets
Multiemployer Plan, Period Contributions	$ 38.8	$ 37.5	$ 30.8