Employee Benefits (Net Periodic Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net periodic benefit cost:
Service cost	$ 6.5	$ 4.6	$ 4.3
Interest cost	55.9	57.2	60.7
Expected return on plan assets	(56.2)	(59.9)	(53.7)
Amortization of prior net loss	13.7	16.0	12.8
Settlement loss	0.0	28.7	0.0
Net periodic pension cost	19.9	46.6	24.1
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (income):
Net actuarial loss (gain) and other adjustments	69.5	(52.0)	126.3
Less amortization of prior losses	(13.7)	(16.0)	(12.8)
Settlement adjustment	0.0	(28.7)	0.0
Total recognized in other comprehensive loss (income)	55.8	(96.7)	113.5
Total recognized in net periodic benefit cost and other comprehensive loss (income)	$ 75.7	(50.1)	137.6
Income tax provision (benefit) related to amounts in other comprehensive income		$ 12.2	$ 0.2