Employee Benefit Plans - Schedule of Fair Value of Plan Assets (Details) - Pension - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 272,974	$ 289,390	$ 257,513
Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	244,383	262,545
Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,591	26,845
Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Money market mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,459	5,236
Money market mutual funds | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,459	5,236
Money market mutual funds | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Money market mutual funds | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - value stock fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,533	27,364
Mutual funds - value stock fund | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,533	27,364
Mutual funds - value stock fund | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - value stock fund | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	115,500	106,726
Mutual funds - fixed income | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	115,500	106,726
Mutual funds - fixed income | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - fixed income | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - international stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,441	40,388
Mutual funds - international stock | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,441	40,388
Mutual funds - international stock | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - international stock | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - institutional stock index
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	73,450	82,831
Mutual funds - institutional stock index | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	73,450	82,831
Mutual funds - institutional stock index | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds - institutional stock index | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,591	26,845
Commingled real estate funds | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled real estate funds | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,591	26,845
Commingled real estate funds | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0