Parent, Guarantor, Non-Guarantor Unaudited Consolidating Condensed Financial Statements - Additional Information (Detail)
|12 Months Ended|
Dec. 31, 2017
|Organization, Consolidation and Presentation of Financial Statements [Abstract]|
|Percentage of guaranteed subsidiaries by the parent companies||100.00%|
Percentage of ownership interest in guarantor subsidiaries by parent companies.
No definition available.