Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0000049071 (http://www.sec.gov/CIK)

Debt Disclosure [Abstract]	Period [Axis]
	2016-01-01 - 2016-12-31
Debt Disclosure [Abstract]
Carrying Value of Long-Term Debt Outstanding	The carrying value of long-term debt outstanding was as follows at December 31, 2016 and 2015:   2016   2015   (in millions) Long-term debt:   Senior notes:   $500 million, 7.20% due June 15, 2018 $ 501   $ 502 $300 million, 6.30% due August 1, 2018 304   307 $400 million, 2.625% due October 1, 2019 398   398 $600 million, 3.15% due December 1, 2022 595   595 $600 million, 3.85% due October 1, 2024 595   595 $250 million, 8.15% due June 15, 2038 264   263 $400 million, 4.625% due December 1, 2042 396   396 $750 million, 4.95% due October 1, 2044 739   738 Total long-term debt $ 3,792   $ 3,794