Long-Term Debt - Financial Covenants Include Required Specified Ratios (Detail)	Sep. 30, 2017
Line Of Credit Facility [Line Items]
Minimum Consolidated Liquidity Ratio	112.00%
Minimum Consolidated Fixed Charge Coverage Ratio	175.00%
Maximum Consolidated Total Lease Adjusted Leverage Ratio	484.00%
Required Ratio [Member]
Line Of Credit Facility [Line Items]
Minimum Consolidated Liquidity Ratio	105.00%
Minimum Consolidated Fixed Charge Coverage Ratio	120.00%
Maximum Consolidated Total Lease Adjusted Leverage Ratio	575.00%