Change in Rate Based on Leverage Ratio (Detail)	Dec. 31, 2012
Less than 3.25 to 1.00 | Base Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	0.75%
Less than 3.25 to 1.00 | EuroDollar Rate Loans
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	2.25%
Less than 3.25 to 1.00 | Applicable Fee Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	0.40%
Greater than or equal to 3.25 to 1.00 but less than 4.50 to 1.00 | Base Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	0.75%
Greater than or equal to 3.25 to 1.00 but less than 4.50 to 1.00 | EuroDollar Rate Loans
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	2.50%
Greater than or equal to 3.25 to 1.00 but less than 4.50 to 1.00 | Applicable Fee Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	0.50%
Greater than or equal to 4.50 to 1.00 but less than 6.00 to 1.00 | Base Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	1.25%
Greater than or equal to 4.50 to 1.00 but less than 6.00 to 1.00 | EuroDollar Rate Loans
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	3.00%
Greater than or equal to 4.50 to 1.00 but less than 6.00 to 1.00 | Applicable Fee Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	0.60%
Greater than or equal to 6.00 to 1.00 | Base Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	2.25%
Greater than or equal to 6.00 to 1.00 | EuroDollar Rate Loans
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	3.50%
Greater than or equal to 6.00 to 1.00 | Applicable Fee Rate
Debt Instrument [Line Items]
Change in rate based on leverage ratio, contractual interest rate	0.75%