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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Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2015	Mar. 31, 2014
4.25% 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
4.0% 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
Convertible Debt [Member] \| 4.25% 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%
Convertible Debt [Member] \| 4.0% 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%
Common Stock [Member]
Earnings Per Share [Line Items]
Weighted average anti-dilutive common stock equivalents (in shares)			807,567	61,226
Common Stock [Member] \| 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued	2,400,000
Common Stock [Member] \| 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued		4,200,000
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)			502,217