Long-term Debt (Narrative) (Details) - USD ($) $ in Millions | Apr. 05, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Mar. 31, 2017 |
Revolving Credit Facility [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, available borrowing capacity | | $ 60 | | |
Term Loan [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility effective interest rate | | 3.63% | 3.06% | |
Credit Agreement [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, maximum borrowing capacity | | $ 125 | | |
Credit Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility effective interest rate | | 3.63% | | |
Credit Agreement [Member] | Federal Funds Rate [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, spread on variable interest rate | | 0.50% | | |
Credit Agreement [Member] | Eurodollar [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, spread on variable interest rate | | 1.00% | | |
Credit Agreement [Member] | Base Rate [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility effective interest rate | | 5.50% | | |
Credit Agreement [Member] | Minimum [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Debt instrument, fixed charge coverage ratio | | 150.00% | | |
Credit facility, interest rate based on leverage ratio | | 0.50% | | |
Credit Agreement [Member] | Minimum [Member] | Subsequent Event [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Debt instrument, fixed charge coverage ratio | 135.00% | | | |
Credit Agreement [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility effective interest rate | | 1.50% | | |
Credit Agreement [Member] | Maximum [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, interest rate based on leverage ratio | | 1.00% | | |
Credit Agreement [Member] | Maximum [Member] | Subsequent Event [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Debt instrument, rent adjusted leverage ratio | 400.00% | | | |
Credit Agreement [Member] | Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility effective interest rate | | 2.00% | | |
Credit Agreement [Member] | Revolving Credit Facility [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, maximum borrowing capacity | | $ 75 | | |
Line of credit outstanding | | 15 | | |
Credit Agreement [Member] | Term Loan [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Credit facility, maximum borrowing capacity | | $ 50 | | |
Credit facility term | | 5 years | | |
Loan payable | | $ 9.5 | | |
Credit Agreement [Member] | Letter of Credit [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Line of credit outstanding | | 1.1 | | $ 1.1 |
June 30, 2018 [Member] | Credit Agreement [Member] | Term Loan [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Quarterly principal payments | | 1.9 | | |
September 30, 2018 to March 31, 2020 [Member] | Credit Agreement [Member] | Term Loan [Member] | | | | |
Debt Instrument [Line Items] | | | | |
Quarterly principal payments | | $ 2.5 | | |