Debt and Subordinated Convertible Debentures Debt and Subordinated Convertible Debentures (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended
	Nov. 30, 2009	Mar. 31, 2013
4 percent Convertible Subordinated Notes [Member]
Debt Instrument [Line Items]
Face amount	$ 173	$ 168
Stated interest rate		4.00%
Hedge transactions cost	26
Hedge transactions cost decreased APIC	17
Convertible note hedge transactions shares (in shares)		15.1
Effective conversion price (in dollars per share)		$ 15.56
Percentage premium over price at issuance		75.00%
Closing price at issuance (in dollars per share)		$ 8.89
ABL Facility [Member]
Debt Instrument [Line Items]
Maximum revolving credit amount percentage		10.00%
Debt terms reference amount to maximum revolving credit		$ 150
Minimum [Member] | 4 percent Convertible Subordinated Notes [Member]
Debt Instrument [Line Items]
Market price per share (in dollars per share)		$ 50.00
Convertible equity shares (in shares)		10.4
Maximum [Member] | 4 percent Convertible Subordinated Notes [Member]
Debt Instrument [Line Items]
Market price per share (in dollars per share)		$ 55.00
Convertible equity shares (in shares)		10.8