3. Debt

The following table summarizes the major components of debt as of each balance sheet date (in millions) and provides the maturities and interest rate ranges of each major category as of March 31, 2018:


	March 31,		December 31,
	2018		2017
$2.25 billion revolving credit facility, maturing July 2020	$	28	$	—
Commercial paper program (weighted average interest rate of 2.3% as of March 31, 2018 and 1.9% as of December 31, 2017)		989		515
Canadian term loan and revolving credit facility, maturing March 2019 (weighted average effective interest rate of 2.8% as of March 31, 2018 and 2.5% as of December 31, 2017)		99		113
Senior notes, maturing through 2045, interest rates ranging from 2.4% to 7.75% (weighted average interest rate of 4.3% as of March 31, 2018 and December 31, 2017)		6,186		6,184
Tax-exempt bonds, maturing through 2045, fixed and variable interest rates ranging from 1.35% to 5.7% (weighted average interest rate of 2.1% as of March 31, 2018 and 2.0% as of December 31, 2017)		2,332		2,352
Capital leases and other, maturing through 2040, interest rates up to 12%		323		327
		9,957		9,491
Current portion of long-term debt		1,056		739
	$	8,901	$	8,752

Debt Classification

As of March 31, 2018, we had $2,180 million of debt maturing within the next 12 months, including (i) $989 million of short-term borrowings under our commercial paper program; (ii) $831 million of tax-exempt bonds with term interest rate periods that expire within the next 12 months, which is prior to their scheduled maturities; (iii) $233 million of other debt with scheduled maturities within the next 12 months, including $181 million of tax-exempt bonds; (iv) C$128 million, or $99 million, of borrowings under our Canadian term loan and (v) $28 million of borrowings under our long-term U.S. credit facility (“$2.25 billion revolving credit facility”). As of March 31, 2018, we have classified $1,124 million of this debt as long-term because we have the intent and ability to refinance these borrowings on a long-term basis as supported by the forecasted available capacity under our $2.25 billion revolving credit facility, as discussed below. The remaining $1,056 million is classified as current obligations.

As of March 31, 2018, we also have $328 million of variable-rate tax-exempt bonds that are supported by letters of credit. The interest rates on our variable-rate tax-exempt bonds are generally reset on either a daily or weekly basis through a remarketing process. All recent tax-exempt bond remarketings have successfully placed Company bonds with investors at market-driven rates and we currently expect future remarketings to be successful. However, if the remarketing agent is unable to remarket our bonds, the remarketing agent can put the bonds to us. In the event of a failed remarketing, we have the intent and ability to refinance these bonds on a long-term basis as supported by the forecasted available capacity under our $2.25 billion revolving credit facility, as discussed below. Accordingly, we have also classified these borrowings as long-term in our Condensed Consolidated Balance Sheet as of March 31, 2018.

Access to and Utilization of Credit Facilities and Commercial Paper Program

$2.25 Billion Revolving Credit Facility — Our $2.25 billion revolving credit facility maturing in July 2020 provides us with credit capacity to be used for either cash borrowings or to support letters of credit or commercial paper. The rates we pay for outstanding loans are generally based on LIBOR plus a spread depending on the Company’s debt rating assigned by Moody’s Investors Service and Standard and Poor’s. As of March 31, 2018, we had $28 million of outstanding borrowings under this facility. We had $603 million of letters of credit issued and $990 million of outstanding borrowings under our commercial paper program (excluding the related discount on issuance), both supported by this facility, leaving unused and available credit capacity of $629 million as of March 31, 2018.

Commercial Paper Program — We have a $1.5 billion commercial paper program that enables us to borrow funds for up to 397 days at competitive interest rates. The commercial paper program is fully supported by our $2.25 billion revolving credit facility. As of March 31, 2018, we had $989 million of outstanding borrowings under our commercial paper program.

Canadian Term Loan and Revolving Credit Facility — We have a Canadian credit agreement (which includes a term loan and revolving credit facility) that matures in March 2019. This agreement provides the Company (i) C$50 million of revolving credit capacity, which can be used for borrowings or letters of credit, and (ii) C$460 million of non-revolving term credit that is prepayable without penalty and principal amounts repaid may not be reborrowed. As of March 31, 2018, we had C$128 million, or $99 million, of outstanding borrowings under our Canadian term loan. As of March 31, 2018, we had no borrowings or letters of credit outstanding under the Canadian revolving credit facility.

Other Letter of Credit Facilities — As of March 31, 2018, we utilized $511 million of other letter of credit facilities, which are both committed and uncommitted, with terms maturing through April 2019.

Debt Borrowings and Repayments

$2.25 Billion Revolving Credit Facility — During the three months ended March 31, 2018, we had borrowings of $28 million under our $2.25 billion revolving credit facility for general corporate purposes.

Commercial Paper Program — During the three months ended March 31, 2018, we had net cash borrowings of $471 million (net of related discount on issuance) to support new business opportunities and for general corporate purposes.

Canadian Term Loan and Revolving Credit Facility — During the three months ended March 31, 2018, we had net repayments of C$14 million, or $11 million, of net advances under our Canadian term loan and revolving credit facility with available cash. The remaining change in the carrying value of outstanding borrowings under our Canadian term loan is due to foreign currency translation.

Tax-Exempt Bonds — During the three months ended March 31, 2018, we repaid $20 million of our tax-exempt bonds with available cash.

Capital Leases and Other — During the three months ended March 31, 2018, we made net repayments of $16 million of other debt with available cash. In addition, during the three months ended March 31, 2018, our other debt increased by $12 million primarily for debt acquired through recent acquisitions.