Fair Value Measures - (Summary Of Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 4,250	$ 27,000
Total short-term investments	93,885	140,490
Total financial assets	98,135	167,490
Interest rate swaps		2,387
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total short-term investments	93,885	135,492
Tradable Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total short-term investments		4,998
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	4,250	27,000
Total short-term investments		140,490
Total financial assets	98,135	167,490
Interest rate swaps		2,387
Significant Other Observable Inputs (Level 2) [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total short-term investments	93,885	135,492
Significant Other Observable Inputs (Level 2) [Member] | Tradable Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total short-term investments		$ 4,998