Fair Value of Financial Instruments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	$ 2,791
Level 1 | Fixed Income Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	818
Level 1 | Stock Index Funds | Small Cap
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	281
Level 1 | Stock Index Funds | Mid Cap
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	284
Level 1 | Stock Index Funds | Large Cap
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	567
Level 1 | Stock Index Funds | International
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	841
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	42
Level 2 | Mexican Peso Forward Contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Assets at Fair Value	$ 42