Long-Term Debt - Schedule of Actual Ratios and Required Ratios Under Financial Covenants (Details)	12 Months Ended
	Dec. 31, 2017
Senior Credit Facility
Debt Instrument [Line Items]
Interest coverage ratio, as defined under the Senior Credit Facility	10.13
Leverage ratio, as defined under the Senior Credit Facility	3.00
Minimum | Senior Credit Facility
Debt Instrument [Line Items]
Interest coverage ratio, as defined under the Senior Credit Facility	2.64
Maximum
Debt Instrument [Line Items]
Leverage ratio, as defined under the Senior Credit Facility	3.25
Maximum | Senior Credit Facility
Debt Instrument [Line Items]
Leverage ratio, as defined under the Senior Credit Facility	3.75