Debt (Tables)

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Short term debt and current portion of long-term debt

	December 31,
	2014		2013
	(millions)
Current portion of 7-year term loan facility expires 2018	$	17	$	15
5.625% senior notes due 2015	148		—
Fair value adjustment on 5.625% senior notes due 2015	1		—
3-year term loan facility expires 2015	1		—
	$	167	$	15

Long-term debt

	December 31,
	2014		2013
	(millions)
7-year term loan facility expires 2018	$	242	$	259
5.625% senior notes due 2015	—		148
Fair value adjustment on 5.625% senior notes due 2015	—		4
4.125% senior notes due 2016	299		299
6.200% senior notes due 2017	394		394
7.000% senior notes due 2019	187		187
5.750% senior notes due 2021	497		496
4.625% senior notes due 2023	249		249
6.125% senior notes due 2043	274		274
3-year term loan facility expires 2015	—		1
	$	2,142	$	2,311

Analysis of interest expense

	Year ended December 31,
	2014		2013		2012
	(millions)
5.625% senior notes due 2015	$	8	$	12	$	12
4.125% senior notes due 2016	13		13		13
6.200% senior notes due 2017	25		33		38
7.000% senior notes due 2019	14		18		21
5.750% senior notes due 2021	30		29		29
4.625% senior notes due 2023	11		4		—
6.125% senior notes due 2043	16		6		—
7-year term loan facility expires 2018	5		6		6
Revolving $800 million credit facility	3		2		1
Revolving $400 million credit facility	4		—		—
Other	6		3		8
Total interest expense	$	135	$	126	$	128