Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Common Stock [Member]
Earnings Per Share [Line Items]
Weighted average anti-dilutive common stock equivalents (in shares)			244,623	0	8,313
4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, repayments (in dollars)	$ 97
Debt instrument, convertible, conversion price (in dollars per share)	$ 15.48		$ 15.48
4.25% Convertible Notes [Member] \| Common Stock [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)	2,400,000
2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price (in dollars per share)	$ 15.48		15.48
2011 4.25% Notes [Member] \| Common Stock [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)	2,200,000
2009 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price (in dollars per share)	$ 15.48		15.48
2009 4.25% Notes [Member] \| Common Stock [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)	200,000
4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, repayments (in dollars)		$ 105
Debt instrument, convertible, conversion price (in dollars per share)	$ 15.76		15.76
4.0% Convertible Notes [Member] \| Common Stock [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)		4,200,000
2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price (in dollars per share)	15.76		15.76
2011 4.0% Notes [Member] \| Common Stock [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)		3,600,000
2009 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price (in dollars per share)	$ 15.76		$ 15.76
2009 4.0% Notes [Member] \| Common Stock [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)		600,000
Convertible Debt [Member] \| 2011 Convertible Notes [Member]
Earnings Per Share [Line Items]
Premium shares (in shares)			4,971,000	6,395,000	2,118,000
Convertible Debt [Member] \| 4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)	$ 100
Debt instrument, convertible, interest rate (percentage)	4.25%		4.25%
Convertible Debt [Member] \| 2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)	$ 97
Debt instrument, convertible, interest rate (percentage)	4.25%		4.25%
Convertible Debt [Member] \| 2009 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)	$ 3
Debt instrument, convertible, interest rate (percentage)	4.25%		4.25%
Convertible Debt [Member] \| 4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)		$ 115
Debt instrument, convertible, interest rate (percentage)	4.00%		4.00%
Convertible Debt [Member] \| 2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)		105
Debt instrument, convertible, interest rate (percentage)	4.00%		4.00%
Convertible Debt [Member] \| 2009 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)		$ 10
Debt instrument, convertible, interest rate (percentage)	4.00%		4.00%