Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Summary of the fair value of financial instruments

The estimated fair values of our other financial instruments at December 31, 2015 and 2014 have been calculated based upon available market information or an appropriate valuation technique, and are as follows:

	December 31, 2015				December 31, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Level 1:
Senior and senior subordinated notes	$	5,916	$	6,030	$	5,984	$	6,390
Level 2:
4 percent Convertible Senior Notes (1)	—		—		32		33
Level 3:
Capital leases (2)	96		95		105		104

(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. The 4 percent Convertible Senior Notes matured in 2015. To exclude the equity component and calculate the fair value as of December 31, 2014, we used an effective interest rate of 7.3 percent.

(2) The fair value of capital leases reflects the present value of the leases using a 7.0 percent interest rate.