Derivative Instruments - Forward Contract Amounts Recorded in Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Total Assets	$ 0	$ 9,210
Total Liabilities	2,045	0
Prepaid Expenses And Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Total Assets	0	9,210
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total Liabilities	$ 2,045	$ 0