DEBT

Our debt balance at March 31, 2015 and December 31, 2014 was as follows (in millions):



	March 31, 2015			December 31, 2014
Total debt	$	2,563		$	2,588
Unamortized issuance costs (a)	(43		)	(44		)
Current maturities	—			—
Debt, net of current maturities and unamortized issuance costs	$	2,520		$	2,544

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(a) Includes unamortized premium of $4 million and $5 million as of March 31, 2015 and December 31, 2014, respectively.

Revolving Credit Facility

As of March 31, 2015, our Revolving Credit Facility provided for total loan availability of $900 million, and we are allowed to request that the loan availability be increased up to an aggregate of $1.5 billion, subject to receiving increased commitments from the lenders. Our Revolving Credit Facility is non-recourse to Tesoro, except for TLGP, and is guaranteed by all of our consolidated subsidiaries, with the exception of Rendezvous Gas Services L.L.C., and secured by substantially all of our assets. Borrowings are available under the Revolving Credit Facility up to the total loan availability of the facility. We had $235 million of borrowings outstanding under the Revolving Credit Facility, resulting in a total unused loan availability of $665 million or 74% of the borrowing capacity as of March 31, 2015. The weighted average interest rate for borrowings under our Revolving Credit Facility was 2.67% at March 31, 2015. The Revolving Credit Facility is scheduled to mature on December 2, 2019.

The Revolving Credit Facility was subject to the following expenses and fees as of March 31, 2015:



Credit Facility	30 day Eurodollar (LIBOR) Rate	Eurodollar Margin	Base Rate	Base Rate Margin	Commitment Fee (unused portion)
Revolving Credit Facility (b)	0.18%	2.50%	3.25%	1.50%	0.50%

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(b) We have the option to elect if the borrowings will bear interest at either a base rate plus the base rate margin, or a Eurodollar rate, for the applicable period, plus the Eurodollar margin at the time of the borrowing. The applicable margin varies based upon a certain leverage ratio, as defined by the Revolving Credit Facility. We also incur commitment fees for the unused portion of the Revolving Credit Facility at an annual rate. Letters of credit outstanding under the Revolving Credit Facility incur fees at the Eurodollar margin rate.