Debt Obligations (Changes In Debt Obligations) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011		Oct. 19, 2011	Dec. 31, 2010		Feb. 28, 2010	Mar. 31, 2008
Debt Instrument [Line Items]
Total debt obligations	$ 2,213			$ 2,321
Total debt obligations, Additions	450
Less current portion	(45)			(140)
Total long-term debt obligations, Additions	405
Less current portion, Additions	(45)
Less current portion Payments, Conversion, Accretion and Other	140
Debt obligations	2,168			2,181
Total debt obligations, payments, conversions, accretion and other	(558)
Total debt obligations ending balance	2,213			2,321
Total long-term debt obligations, payments, conversions, accretion and other	(418)
3.75% Convertible Notes Due October 22, 2012 [Member]
Debt Instrument [Line Items]
Total debt obligations		[1]			[1]
Debt Instrument, Increase, Additional Borrowings		[1]
Payments, conversions, accretion and other		[1]
Total debt obligations ending balance		[1]			[1]
Debt instrument, interest rate	3.75%			3.75%
Debt instrument, maturity date	Oct. 22, 2012
Debt instrument, principal outstanding	0.5			0.5
2.50% Convertible Senior Notes Due August 15, 2013 [Member]
Debt Instrument [Line Items]
Total debt obligations	399	[2]		388	[2]
Debt Instrument, Increase, Additional Borrowings		[2]
Payments, conversions, accretion and other	11	[2]
Total debt obligations ending balance	399	[2]		388	[2]
Debt instrument, interest rate	2.50%					2.50%	2.50%
Debt instrument, maturity date	Aug. 15, 2013
Debt instrument, principal outstanding	428.0		335.0	428.0			475.0
4.00% Senior Unsecured Notes Due January 15, 2015 [Member]
Debt Instrument [Line Items]
Total debt obligations	399	[3]		398	[3]
Debt Instrument, Increase, Additional Borrowings		[3]
Payments, conversions, accretion and other	1	[3]
Total debt obligations ending balance	399	[3]		398	[3]
Debt instrument, interest rate	4.00%
Debt instrument, maturity date	Jan. 15, 2015
5.55% Senior Unsecured Notes Due January 15, 2020 [Member]
Debt Instrument [Line Items]
Total debt obligations	598	[3]		598	[3]
Debt Instrument, Increase, Additional Borrowings		[3]
Total debt obligations ending balance	598	[3]		598	[3]
Debt instrument, interest rate	5.55%
Debt instrument, maturity date	Jan. 15, 2020
5.25% Senior Unsecured Notes Due January 16, 2018 [Member]
Debt Instrument [Line Items]
Total debt obligations	367	[3]		367	[3]
Debt Instrument, Increase, Additional Borrowings		[3]
Total debt obligations ending balance	367	[3]		367	[3]
Debt instrument, interest rate	5.25%
Debt instrument, maturity date	Jan. 16, 2018
$450 Million Senior Unsecured Term Loan Facility Credit Agreement Due September 19, 2016 [Member]
Debt Instrument [Line Items]
Total debt obligations, Additions	450	[4]
Debt Instrument, Interest Rate During Period	1.60%
Debt instrument, maturity date	Sep. 19, 2016
Debt instrument, principal outstanding	450.0
$700 Million Senior Unsecured Term Loan Facility Credit Agreement Due September 19, 2011 [Member]
Debt Instrument [Line Items]
Total debt obligations				570	[5]
Debt Instrument, Increase, Additional Borrowings		[5]
Payments, conversions, accretion and other	(570)	[5]
Total debt obligations ending balance				570	[5]
Debt Instrument, Interest Rate During Period	2.25%
Debt instrument, maturity date	Sep. 19, 2011
Debt instrument, principal outstanding	$ 700.0

[1] As of September 30, 2011 and December 31, 2010, approximately $0.5 million aggregate principal amount of the 3.75% convertible notes remained outstanding

[2] See "2.50% Convertible Senior Notes" below for further discussion.

[3] See "Senior Unsecured Notes" below for further discussion.

[4] See "2011 Credit Facility" below for further discussion.

[5] See "2010 Credit Facility" below for further discussion.