Employee Benefit Plans - Schedule of the Weighted-Average Asset Allocations of the Pension Plans (Details)	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation (as a percent)	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation (as a percent)	17.60%	20.80%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation (as a percent)	34.60%	34.50%
Other
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation (as a percent)	47.80%	44.70%