Employee Benefit Plans - Schedule of Allocation of Plan Assets (Details)	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	100.00%
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	1.00%
Defined Benefit Plan, Actual Plan Asset Allocations	6.10%	6.90%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	68.00%
Defined Benefit Plan, Actual Plan Asset Allocations	68.90%	65.50%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	31.00%
Defined Benefit Plan, Actual Plan Asset Allocations	25.00%	27.60%