Fair Value Measurements (Details) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011		Dec. 31, 2010		Sep. 30, 2010	Dec. 31, 2009
Cash and cash equivalents	$ 599,545		$ 368,134		$ 390,008	$ 670,992
Short-term investments	249,816		402,882
Long-term investments	85,676		102,185
Long term investment maturities - begin	13 months from September 30, 2011
Long term investment maturities - end	23 months from September 30, 2011
Fair Value
Cash and cash equivalents	599,545		368,134
Long-term debt	1,516,835	[1]	1,482,181	[1]
Fair Value | Certificates Of Deposit
Short-term investments	53,584	[2],[3]	97,270	[2],[3]
Fair Value | Government Backed Securities
Short-term investments	196,232	[2],[3],[4]	305,612	[2],[3],[4]
Long-term investments	86,058	[2],[4],[5]	102,325	[2],[4],[5]
Book Value
Cash and cash equivalents	599,545		368,134
Long-term debt	1,523,936	[1]	1,495,461	[1]
Book Value | Certificates Of Deposit
Short-term investments	53,584	[2],[3]	97,270	[2],[3]
Book Value | Government Backed Securities
Short-term investments	196,232	[2],[3],[4]	305,612	[2],[3],[4]
Long-term investments	$ 85,676	[2],[4],[5]	$ 102,185	[2],[4],[5]

[1] Excludes capital lease obligations and current portion of Long-term debt.

[2] Designated as held-to-maturity investments and recorded at amortized cost in the Consolidated Balance Sheet.

[3] Maturities are less than twelve months from the respective balance sheet dates.

[4] Includes U.S. treasuries and corporate notes guaranteed under the Federal Deposit Insurance Corporation’s Temporary Liquidity Guarantee Program.

[5] At September 30, 2011, maturities range between 13 and 23 months.