10. Debt

The components of debt and a reconciliation to the carrying amount of long-term debt is presented in the table below.

	March 31, 2017			December 31, 2016
	(in millions)
Borrowings under Revolving Credit Facility⁽¹⁾	$	—		$	—
5.20% Senior Notes due 2019		1,000			1,000
4.75% Senior Notes due 2020		800			800
4.95% Senior Notes due 2021		650			650
3.95% Senior Notes due 2024		350			350
3.85% Senior Notes due 2026		550			550
Principal amount of long-term debt		3,350			3,350
Unamortized discounts		(8	)		(8	)
Deferred debt issue costs		(16	)		(17	)
Carrying amount of long-term debt	$	3,326		$	3,325

⁽¹⁾

During the quarterly period ended March 31, 2017, L3’s aggregate borrowings and repayments under the Credit Facility were $664 million. At March 31, 2017, L3 had the full availability of its $1 billion Credit Facility.