Debt

3 Months Ended

Mar. 31, 2012

Debt [Abstract]

Debt

3.    Debt

The following table summarizes the major components of debt at each balance sheet date (in millions) and provides the maturities and interest rate ranges of each major category as of March 31, 2012:

	March 31, 2012		December 31, 2011
Revolving credit facility (interest rate of 1.4% at March 31, 2012 and 1.5% at December 31, 2011)	$	300	$	150
Letter of credit facilities		—		—
Canadian credit facility (weighted average effective interest rate of 1.6% at March 31, 2012 and 1.8% at December 31, 2011)		115		137
Senior notes and debentures, maturing through 2039, interest rates ranging from 2.60% to 7.75% (weighted average interest rate of 6.0% at March 31, 2012 and December 31, 2011)		6,223		6,228
Tax-exempt bonds, maturing through 2041, fixed and variable interest rates ranging from 0.2% to 7.4% (weighted average interest rate of 3.1% at March 31, 2012 and December 31, 2011)		2,736		2,771
Tax-exempt project bonds, maturing through 2029, fixed and variable interest rates ranging from 0.2% to 3.4% (weighted average interest rate of 1.4% at March 31, 2012 and 1.3% at December 31, 2011)		86		86
Capital leases and other, maturing through 2055, interest rates up to 12%		389		384
		9,849		9,756
Current portion of long-term debt		860		631
	$	8,989	$	9,125

Debt Classification

As of March 31, 2012, we had $1,005 million of debt maturing within the next twelve months, including $300 million of borrowings outstanding under the revolving credit facility, U.S. $115 million of advances outstanding under our Canadian credit facility, $400 million of 6.375% senior notes that mature in November 2012 and $134 million of tax-exempt bonds. We have classified $145 million of these borrowings as long-term as of March 31, 2012 based on our intent and ability to refinance these borrowings on a long-term basis. We also had $429 million of fixed-rate tax-exempt borrowings subject to repricing within the next twelve months, which were classified as long-term based on our intent and ability to fund any failed remarketings with available capacity under our revolving credit facility.

Revolving Credit and Letter of Credit Facilities

As of March 31, 2012, we had an aggregate committed capacity of $2.5 billion for letters of credit under various credit facilities. In May 2011, we amended and restated our $2.0 billion revolving credit facility as a result of changes in market conditions, which significantly reduced the cost of the facility. We also extended the term through May 2016. Our revolving credit facility is our primary source of letter of credit capacity. Our remaining letter of credit capacity is provided under facilities with terms that extend from June 2013 to June 2015. As of March 31, 2012, we had an aggregate of $1.5 billion of letters of credit outstanding under various credit facilities. Approximately $1.0 billion of these letters of credit have been issued under our revolving credit facility. We had $300 million of outstanding borrowings under our revolving credit facility as of March 31, 2012.

Debt Borrowings and Repayments

During the first quarter of 2012, we borrowed $150 million under our revolving credit facility for general corporate purposes. We also repaid $25 million of net advances under our Canadian credit facility and $35 million of tax-exempt bonds with available cash during the three months ended March 31, 2012.