Required and Actual Financial Ratios Under Senior Secured Credit Facility (Detail) (Senior Secured Credit Facility)	Dec. 31, 2011 Point
Required Ratio | Maximum
Debt Instrument [Line Items]
Consolidated leverage ratio	3.50
Required Ratio | Minimum
Debt Instrument [Line Items]
Consolidated interest coverage ratio	3.00
Actual Ratio | Maximum
Debt Instrument [Line Items]
Consolidated leverage ratio	1.88
Actual Ratio | Minimum
Debt Instrument [Line Items]
Consolidated interest coverage ratio	10.18