Employee Benefit Plans - Schedule of Changes in Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 27,977	$ 24,482	$ 25,190
Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26,282	22,795
Money Market Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,695	1,687
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27,977	24,482
Fair Value, Inputs, Level 1 | Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26,282	22,795
Fair Value, Inputs, Level 1 | Money Market Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,695	1,687
Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Inputs, Level 2 | Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Inputs, Level 2 | Money Market Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Inputs, Level 3 | Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Inputs, Level 3 | Money Market Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0