Employee Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 59,737	$ 65,728	$ 57,723
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	59,737	65,728
Pension | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	30,281	32,626
Pension | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	29,456	33,102
Pension | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Large cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	15,141	16,313
Pension | U.S. equities, Large cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Large cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	15,141	16,313
Pension | U.S. equities, Large cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Medium cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,137
Pension | U.S. equities, Medium cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Medium cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,137
Pension | U.S. equities, Medium cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Small cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,330	2,510
Pension | U.S. equities, Small cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,165	1,255
Pension | U.S. equities, Small cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,165	1,255
Pension | U.S. equities, Small cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Large cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	11,065	11,922
Pension | Non-U.S. equities, Large cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	11,065	11,922
Pension | Non-U.S. equities, Large cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Large cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Emerging markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3,494	3,765
Pension | Non-U.S. equities, Emerging markets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3,494	3,765
Pension | Non-U.S. equities, Emerging markets | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Emerging markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Money markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,133
Pension | Money markets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Money markets | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,133
Pension | Money markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. bonds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	11,647	12,548
Pension | U.S. bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	8,735	9,411
Pension | U.S. bonds | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,137
Pension | U.S. bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. bonds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	5,822	6,273
Pension | Non-U.S. bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	5,822	6,273
Pension | Non-U.S. bonds | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,137
Pension | Real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Real estate | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,912	3,137
Pension | Real estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Common/collective trusts
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,502	2,990
Pension | Common/collective trusts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Common/collective trusts | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,502	2,990
Pension | Common/collective trusts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 0	$ 0