Employee Benefit Plans - Summary of Pension Plan Asset Allocations By Asset Category (Details)	Dec. 31, 2017	Dec. 31, 2016
Pension plan assets target allocation [Abstract]
Plan asset target percentage	100.00%
Pension plan assets actual allocation [Abstract]
Plan assets actual percentage	100.00%	100.00%
U.S. Equity Securities [Member]
Pension plan assets target allocation [Abstract]
Plan asset target percentage	27.00%
Pension plan assets actual allocation [Abstract]
Plan assets actual percentage	30.00%	32.70%
Non-U.S. Equity Securities [Member]
Pension plan assets target allocation [Abstract]
Plan asset target percentage	39.00%
Pension plan assets actual allocation [Abstract]
Plan assets actual percentage	41.70%	35.10%
Fixed Income Securities [Member]
Pension plan assets target allocation [Abstract]
Plan asset target percentage	30.00%
Pension plan assets actual allocation [Abstract]
Plan assets actual percentage	23.20%	27.20%
Other Mutual Funds [Member]
Pension plan assets target allocation [Abstract]
Plan asset target percentage	4.00%
Pension plan assets actual allocation [Abstract]
Plan assets actual percentage	5.10%	5.00%