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 number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of contingently issuable shares. Contingently issuable shares are those shares that are issuable for little or no cash contingent on certain conditions being met.

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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		3 Months Ended		9 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, repayments (in dollars)		$ 105
Debt instrument, convertible, conversion price per share (in dollars per share)		$ 15.76
2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)		15.76
2009 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)		$ 15.76
4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, repayments (in dollars)	$ 97
Debt instrument, convertible, conversion price per share (in dollars per share)	$ 15.48
2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)	15.48
2009 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)	$ 15.48
Convertible Debt [Member]
Earnings Per Share [Line Items]
Premium shares (in shares)			0	3,199,000	0	6,460,000
Convertible Debt [Member] \| 2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Premium shares (in shares)						2,400,000
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%
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%
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%
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%
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%
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%
Common Stock [Member]
Earnings Per Share [Line Items]
Weighted average anti-dilutive common stock equivalents (in shares)			0	304,486	648,379	223,422
Common Stock [Member] \| 4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)		4,200,000
Common Stock [Member] \| 4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)	2,400,000
Common Stock [Member] \| Common Stock Equivalents Excluded Due To Net Loss [Member]
Earnings Per Share [Line Items]
Weighted average anti-dilutive common stock equivalents (in shares)					648,379