7. Debt

Debt consists of (in millions):


	June 30,		December 31,
	2017		2016
$500 million in Senior Notes, interest at 1.35% payable semiannually, principal due on December 1, 2017	$	499	$	499
$1.4 billion in Senior Notes, interest at 2.60% payable semiannually, principal due on December 1, 2022		1,392		1,391
$1.1 billion in Senior Notes, interest at 3.95% payable semiannually, principal due on December 1, 2042		1,087		1,087
Other		236		237

Total debt		3,214		3,214
Less current portion		506		506

Long-term debt	$	2,708	$	2,708

On June 27, 2017, the Company entered into a new $3.0 billion credit agreement evidencing a five-year unsecured revolving credit facility, which expires on June 27, 2022, with a syndicate of financial institutions. This new credit facility replaced the Company’s previous $4.5 billion revolving credit facility. The Company has the right to increase the aggregate commitments under this new agreement to an aggregate amount of up to $4.0 billion upon the consent of only those lenders holding any such increase. Interest under the new multicurrency facility is based upon LIBOR, NIBOR or CDOR plus 1.125% subject to a ratings-based grid or the U.S. prime rate. The new credit facility contains a financial covenant regarding maximum debt-to-capitalization ratio of 60%. As of June 30, 2017, the Company was in compliance with a debt-to-capitalization ratio of 18.6%.

The Company has a commercial paper program under which borrowings are classified as long-term since the program is supported by the $3.0 billion, five-year credit facility. At June 30, 2017, there were no commercial paper borrowings, and there were no outstanding letters of credit issued under the credit facility, resulting in $3.0 billion of funds available under this credit facility.

The Company had $833 million of outstanding letters of credit at June 30, 2017 that are under various bilateral letter of credit facilities. Letters of credit are issued as bid bonds, advanced payment bonds and performance bonds.

The fair value of the Company’s debt is estimated using Level 2 inputs in the fair value hierarchy and is based on quoted prices for those or similar instruments. At June 30, 2017 and December 31, 2016, the fair value of the Company’s unsecured Senior Notes approximated $2,766 million and $2,669 million, respectively. At June 30, 2017 and December 31, 2016, the carrying value of the Company’s unsecured Senior Notes approximated $2,978 million and $2,977 million, respectively.