Fair Value Measurements (Schedule Of Assets And Liabilities Carried At Fair Value Measured On A Recurring Basis) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 530,385	[1]	$ 605,303	[1]
Restricted cash	8,182	[2]	6,281	[2]
Short-term investments	0	[2]	4,879	[2]
Total	538,567		616,463
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	[1]	0	[1]
Restricted cash	0	[2]	0	[2]
Short-term investments	0	[2]	0	[2]
Total	0		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	[1]	0	[1]
Restricted cash	0	[2]	0	[2]
Short-term investments	0	[2]	0	[2]
Total	0		0
Portion at Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	530,385	[1]	605,303	[1]
Restricted cash	8,182	[2]	6,281	[2]
Short-term investments	0	[2]	4,879	[2]
Total	538,567		616,463
Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 146,900		$ 407,400

[1] Cash and cash equivalents consist primarily of money market funds with original maturity dates of three months or less, which are Level 1 assets. At June 30, 2013 and December 31, 2012, we had $146.9 million and $407.4 million, respectively, in money market funds.

[2] Restricted cash and short-term investments with original maturities greater than three months are classified as “Prepaid expenses and other” on our Condensed Consolidated Balance Sheets.