Employee Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of net periodic benefit cost
Pension settlement	$ 0	$ 31,400,000	$ 0
Discontinued Operations [Member]
Components of net periodic benefit cost
Total net periodic benefit cost	4,400,000.0
Pension Benefits [Member]
Components of net periodic benefit cost
Service cost	5,000,000	4,400,000	4,800,000
Interest cost	12,600,000	15,300,000	17,200,000
Expected return on plan assets	(21,300,000)	(21,500,000)	(21,400,000)
Amortization of prior service cost	200,000	300,000	200,000
Amortization of net loss	8,100,000	7,600,000	9,500,000
Settlements or curtailments	700,000	31,600,000	400,000
Total net periodic benefit cost	5,300,000	37,700,000	10,700,000
Other Benefits [Member]
Components of net periodic benefit cost
Service cost	0	0	0
Interest cost	100,000	100,000	200,000
Expected return on plan assets	0	0	0
Amortization of prior service cost	(2,400,000)	(3,000,000)	(3,100,000)
Amortization of net loss	1,400,000	1,400,000	1,500,000
Settlements or curtailments	0	0	0
Total net periodic benefit cost	$ (900,000)	$ (1,500,000)	$ (1,400,000)