Fair Value Measurements (Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Level 1 [Member] | Carrying Amount [Member]
Level 1:
Subordinated convertible debentures	$ 55		$ 55
Senior and senior subordinated notes	5,480		1,732
Level 1 [Member] | Fair Value [Member]
Level 1:
Subordinated convertible debentures	55		49
Senior and senior subordinated notes	5,737		1,795
Level 2 [Member] | Carrying Amount [Member]
Level 2:
4 percent Convertible Senior Notes (1)	133	[1]	129	[1]
Level 2 [Member] | Fair Value [Member]
Level 2:
4 percent Convertible Senior Notes (1)	148	[1]	138	[1]
Level 3 [Member] | Carrying Amount [Member]
Level 3:
Capital leases (2)	132	[2]	39	[2]
Level 3 [Member] | Fair Value [Member]
Level 3:
Capital leases (2)	$ 117	[2]	$ 33	[2]
4 percent Convertible Subordinated Notes [Member]
Level 3:
Stated interest rate	4.00%
Effective interest rate	8.00%
Capital Leases [Member]
Level 3:
Effective interest rate	7.00%

[1] The fair value of the 4 percent Convertible Senior Notes is based on the market value of comparable notes. Consistent with the carrying amount, the fair value excludes the equity component of the notes. To exclude the equity component and calculate the fair value, we used an effective interest rate of 8.0 percent.

[2] The fair value of capital leases reflects the present value of the leases, which was determined using a 7.0 percent interest rate.