Cash and Cash Equivalent Balances (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents in domestic accounts	$ 334,567	$ 263,853
Cash and cash equivalents in foreign accounts	84,076	52,484
Total	$ 418,643	$ 316,337	$ 263,334	$ 394,795