The carrying value of long-term debt outstanding, net of unamortized debt issuance costs, was as follows at September 30, 2018 and December 31, 2017:



	September 30, 2018		December 31, 2017
	(in millions)
Senior notes:
$400 million, 2.625% due October 1, 2019	$	399	$	399
$400 million, 2.50% due December 15, 2020	398		397
$400 million, 2.90% due December 15, 2022	396		396
$600 million, 3.15% due December 1, 2022	597		595
$600 million, 3.85% due October 1, 2024	596		595
$600 million, 3.95% due March 15, 2027	595		594
$250 million, 8.15% due June 15, 2038	263		263
$400 million, 4.625% due December 1, 2042	396		396
$750 million, 4.95% due October 1, 2044	739		739
$400 million, 4.80% due March 15, 2047	395		396
Total long-term debt	$	4,774	$	4,770