Long-Term Debt and Credit Facility - Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Long-term debt, term note and notes payable:
Total	$ 374,026	$ 355,422
Less – Current maturities and notes payable	19,835	17,648
Debt Issuance Costs, Net	3,406	4,294
Long-term debt, less current maturities	$ 350,785	$ 333,480
Medium-term Notes
Debt Instrument [Line Items]
Debt annualized rates (as percent)	3.08%	2.47%
Long-term debt, term note and notes payable:
Term notes	$ 328,125	$ 345,625
Line of Credit
Debt Instrument [Line Items]
Debt annualized rates (as percent)	2.96%
Long-term debt, term note and notes payable:
Line of credit, 2.96%	$ 36,000	0
Notes Payable, Other Payables
Long-term debt, term note and notes payable:
Other notes with interest rates from 3.3% to 6.5%	$ 9,901	$ 9,797
Minimum | Notes Payable, Other Payables
Debt Instrument [Line Items]
Current stated interest rate	3.30%	3.30%
Maximum | Notes Payable, Other Payables
Debt Instrument [Line Items]
Current stated interest rate	6.50%	6.50%