Schedule Of Financial Assets And Liabilities Subject To Fair Value Measurement Provisions (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Apr. 01, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 30,213	$ 36,093
Liabilities, Fair Value Disclosure	(1,634)	(555)
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0		0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0		0
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	29,715	34,600
Liabilities, Fair Value Disclosure	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	498	1,493
Liabilities, Fair Value Disclosure	(1,634)	(555)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Derivative Financial Instruments, Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liabilities, Fair Value Disclosure	(1,634)	(555)
Derivative Financial Instruments, Liabilities [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liabilities, Fair Value Disclosure	0	0
Derivative Financial Instruments, Liabilities [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liabilities, Fair Value Disclosure	(1,634)	(555)
Derivative Financial Instruments, Liabilities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liabilities, Fair Value Disclosure	0	0
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	29,480	34,403
Money Market Funds [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	29,480	34,403
Money Market Funds [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Money Market Funds [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	235	197
Stock [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	235	197
Stock [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Stock [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Derivative Financial Instruments, Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	498	1,493
Derivative Financial Instruments, Assets [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Derivative Financial Instruments, Assets [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	498	1,493
Derivative Financial Instruments, Assets [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 0	$ 0