Estimated Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 570,854	$ 403,463
Restricted cash and cash equivalents, Carrying Amount	21,962	197,861
Investments, Carrying Amount	139,006	285,205
Debt, Carrying Amount	93,735	55,295
Forward contracts, Carrying Amount	(5,029)	1,352
Cash and cash equivalents	570,854	403,463
Restricted cash and cash equivalents, Fair Value	21,962	197,861
Investments, Fair Value	139,006	285,205
Debt, Fair Value	96,187	56,180
Forward contracts, Fair Value	$ (5,029)	$ 1,352

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

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