(Stated in millions)

	Mar. 31,		Dec. 31,
	2019		2018
4.00% Senior Notes due 2025	$	1,743	$	1,742
3.30% Senior Notes due 2021		1,597		1,596
3.00% Senior Notes due 2020		1,596		1,596
3.65% Senior Notes due 2023		1,494		1,493
4.20% Senior Notes due 2021		1,100		1,100
2.40% Senior Notes due 2022		997		997
3.63% Senior Notes due 2022		847		847
3.75% Senior Notes due 2024		745		-
4.30% Senior Notes due 2029		844		-
1.00% Guaranteed Notes due 2026		671		678
2.65% Senior Notes due 2022		598		598
2.20% Senior Notes due 2020		499		499
7.00% Notes due 2038		209		210
4.50% Notes due 2021		132		132
5.95% Notes due 2041		115		115
3.60% Notes due 2022		109		109
5.13% Notes due 2043		99		99
4.00% Notes due 2023		81		82
3.70% Notes due 2024		55		55
Commercial paper borrowings		2,655		2,433
Other		263		263
	$	16,449	$	14,644

The estimated fair value of Schlumberger’s Long-term Debt, based on quoted market prices at March 31, 2019 and December 31, 2018, was $16.7 billion and $14.6 billion, respectively.

At March 31, 2019, Schlumberger had separate committed credit facility agreements aggregating $6.5 billion with commercial banks, of which $3.8 billion was available and unused. These committed facilities support commercial paper programs in the United States and Europe, of which $1.0 billion matures in February 2020, $1.5 billion matures in November 2020, $2.0 billion matures in February 2023 and $2.0 billion matures in February 2024. Interest rates and other terms of borrowing under these lines of credit vary by facility.

Borrowings under Schlumberger’s commercial paper programs at March 31, 2019 and December 31, 2018 were $2.7 billion and $2.4 billion, respectively, all of which were classified in Long-term Debt in the Consolidated Balance Sheet.

In April 2019, Schlumberger completed a debt exchange offer, pursuant to which it issued $1.500 billion in principal of 3.90% Senior Notes due 2028 (the “New Notes”) in exchange for $401 million of 3.00% Senior Notes due 2020, $234 million of 3.63% Senior Notes due 2022 and $817 million of 4.00% Senior Notes due 2025. In connection with the exchange of principal, Schlumberger paid a premium of $48 million, substantially all of which was in the form of New Notes. This premium will be amortized as additional interest expense over the term of the New Notes.