	June 30,		December 31,
	2021		2020
$1.1 billion in Senior Notes, interest at 3.95% payable semiannually, principal due on December 1, 2042	$	1,089	$	1,089
$0.5 billion in Senior Notes, interest at 3.60% payable semiannually, principal due on December 1, 2029		494		493
$0.2 billion in Senior Notes, interest at 2.60% payable semiannually, principal due on December 1, 2022		-		182
Other debt		103		70
Total	$	1,686	$	1,834

The Company has a $2.0 billion, five-year unsecured revolving credit facility, which expires on October 30, 2024. The Company has the right to increase the commitments under this agreement to an aggregate amount of up to $3.0 billion upon the consent of only those lenders holding any such increase. Interest under the 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 credit facility contains a financial covenant regarding maximum debt-to-capitalization ratio of 60%. As of June 30, 2021, the Company was in compliance with a debt-to-capitalization ratio of 27.2% and had no outstanding letters of credit issued under the facility, resulting in $2.0 billion of available funds.

Additionally, the Company has a $150 million bank line of credit for the construction of a facility in Saudi Arabia. Interest under the bank line of credit is based upon LIBOR plus 1.40%. The bank line of credit contains a financial covenant regarding maximum debt-to-equity ratio of 75%. As of June 30, 2021, the Company was in compliance. Other debt at June 30, 2021 included $25 million of funding provided by a minority interest partner of an NOV consolidated joint venture.

On April 8, 2021, the Company extended the maturity date of the revolving credit facility by one additional year to October 30, 2025. The revolving credit facility has a borrowing capacity of $2.0 billion through October 30, 2024, and a borrowing capacity of $1.655 billion from October 31, 2024, to October 30, 2025.

On April 9, 2021, the Company repaid the entire outstanding balance of $182 million of its 2.60% unsecured Senior Notes due December 1, 2022 using available cash balances. Upon redemption, the Company paid $191 million, which included a redemption premium of $6.8 million as well as accrued and unpaid interest of $1.7 million. As a result of the redemption, the Company recorded a loss on extinguishment of debt of $7.1 million in the second quarter, including a make whole premium of $6.8 million and non-cash charges of $0.3 million to write-off unamortized discount and debt issuance costs. Following the repayment, the Company’s earliest bond maturity is in 2029.

The Company had $470 million of outstanding letters of credit at June 30, 2021, primarily in the U.S. and Norway, that are under various bilateral letter of credit facilities. Letters of credit are issued as bid bonds, advanced payment bonds and performance bonds.

At June 30, 2021 and December 31, 2020, the fair value of the Company’s unsecured Senior Notes approximated $1,610 million and $1,833 million, respectively. 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 of similar instruments. At June 30, 2021 and December 31, 2020, the carrying value of the Company’s unsecured Senior Notes approximated $1,583 million and $1,764 million, respectively.