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Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
Employee Benefit Plans (Narrative) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed	5.70%
Ultimate trend rate	4.50%
Effect of one percentage point increase on postretirement benefit obligation	$ 8,700,000
Effect of one percentage point increase on postretirement benefit cost	$ 400,000
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (percent)	27.00%
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (percent)	73.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation of pension plans	$ 217,500,000	$ 228,900,000
Expected amortization of prior service credit, next fiscal year	100,000
Pension contributions planned for next fiscal year	0
Other postretirement benefits payments	17,500,000	$ 17,900,000	$ 18,000,000.0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected amortization of gain, next fiscal year	$ 2,100,000