Debt (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Summary of Short-term and Long-term Debt Outstanding

A summary of short-term and long-term debt outstanding is as follows:

(in millions)	December 31,
	2016		2015
5.9% Senior Notes, due 2017 1	$	—	$	399
2.5% Senior Notes, due 2018 2	398		398
3.3% Senior Notes, due 2020 3	696		695
4.0% Senior Notes, due 2025 4	691		690
4.4% Senior Notes, due 2026 5	891		890
2.95% Senior Notes, due 20276	492		—
6.55% Senior Notes, due 2037 7	396		396
Commercial paper	—		143
Total debt	3,564		3,611
Less: short-term debt including current maturities	—		143
Long-term debt	$	3,564	$	3,468

¹  We made a $400 million early repayment of our 5.9% senior notes on October 20, 2016.

²  Interest payments are due semiannually on February 15 and August 15, and as of December 31, 2016, the unamortized debt discount and issuance costs total $2 million.

³  Interest payments are due semiannually on February 14 and August 14, and as of December 31, 2016, the unamortized debt discount and issuance costs total $4 million.

⁴  Interest payments are due semiannually on June 15 and December 15, and as of December 31, 2016, the unamortized debt discount and issuance costs total $9 million.

⁵  Interest payments are due semiannually on February 15 and August 15, and as of December 31, 2016, the unamortized debt discount and issuance costs total $9 million.

⁶  Interest payments are due semiannually on January 22 and July 22, beginning on January 22, 2017, and as of December 31, 2016, the unamortized debt discount and issuance costs total $8 million.

⁷  Interest payments are due semiannually on May 15 and November 15, and as of December 31, 2016, the unamortized debt discount and issuance costs total $4 million.