Assets and Liabilities Measured at Fair Value on Non-recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Lease termination closure accruals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets measured on nonrecurring basis	$ 541
Facility impairment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets measured on nonrecurring basis	856
Fair Value, Inputs, Level 3 | Lease termination closure accruals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets measured on nonrecurring basis	541
Fair Value, Inputs, Level 3 | Facility impairment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets measured on nonrecurring basis	$ 856