Employee Benefits (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 124.5	$ 117.4
Pension Plan and SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		100.00%	100.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		6.00%	6.00%
SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	6.00%
Employee Investment Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%	100.00%	100.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	8.00%	8.00%	8.00%
Defined Contribution Plan, Cost Recognized	$ 5.6	$ 6.3	$ 7.6
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	4.0
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 4.0
Defined Benefit Plan, Curtailment loss		11.2	10.7
Defined Benefit Plan, Special termination benefits			1.9
Pension Plan [Member] | Active Employees [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Number of Employees Covered	41
Defined Benefit Plan, Percentage Of Employees Covered	6.00%
Pension Plan [Member] | Non-active Employees [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Number of Employees Covered	173
Pension Plan and SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	$ 7.2	7.5
Defined Benefit Plan, Curtailment loss	0.0	11.2	9.3
Defined Benefit Plan, Special termination benefits	0.0	0.0	1.9
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	$ 2.2
Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Number of Eligible	25
Defined Benefit Plan, Number of Employees Covered	50
Defined Benefit Plan, Contributions by Employer	$ 0.4	0.2
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	0.3
Defined Benefit Plan, Curtailment loss	0.0	0.0	1.4
Defined Benefit Plan, Special termination benefits	0.0	$ 0.0	$ 0.0
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	0.2
SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	3.2
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 2.5