Fair Value Measurements (Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Level 1 [Member] | Carrying Amount [Member]
Level 1:
Subordinated convertible debentures	$ 55		$ 55
Senior and senior subordinated notes	4,558		1,732
Level 1 [Member] | Fair Value [Member]
Level 1:
Subordinated convertible debentures	60		49
Senior and senior subordinated notes	4,790		1,795
Level 2 [Member] | Carrying Amount [Member]
Level 2:
Convertible Debt, Fair Value Disclosures	131		129
Level 2 [Member] | Fair Value [Member]
Level 2:
Convertible Debt, Fair Value Disclosures	145		138
Level 3 [Member] | Carrying Amount [Member]
Level 3:
Capital leases	38	[1]	39	[1]
Level 3 [Member] | Fair Value [Member]
Level 3:
Capital leases	$ 31	[1]	$ 33	[1]

[1] The fair value of capital leases is determined using the expected present value of the leases.