Debt (Tables)

3 Months Ended

Mar. 31, 2013

Debt Disclosure [Abstract]

Short-term and long-term debt outstanding

(in millions)	March 31, 2013		December 31, 2012
5.9% Senior Notes, due 2017 1	400		400
6.55% Senior Notes, due 2037 2	399		399
Commercial paper	—		457
Total debt	799		1,256
Less: short-term debt including current maturities	—		457
Long-term debt	$	799	$	799

¹  Interest payments are due semiannually on April 15 and October 15, and, as of March 31, 2013, the unamortized debt discount is $0.4 million.

²  Interest payments are due semiannually on May 15 and November 15, and, as of March 31, 2013, the unamortized debt discount is $1.3 million.