Fair Value Measurement (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 294,068	[1]	$ 202,276	[1]
Interest rate swap contracts	23,539		19,091
Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	294,068	[1]	202,276	[1]
Interest rate swap contracts
Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		[1]
Interest rate swap contracts	23,539		19,091
Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		[1]		[1]
Interest rate swap contracts

[1] Represents the Company's investment in money market funds.