June 30,

December 31,

2019

2018

$2.75 billion revolving credit facility (weighted average interest rate of 3.1% as of December 31, 2018)

$

—

$

11

Commercial paper program (weighted average interest rate of 2.9% as of December 31, 2018)

—

990

Senior notes, maturing through 2049, interest rates ranging from 2.4% to 7.75% (weighted average interest rate of 3.9% as of June 30, 2019 and 4.3% as of December 31, 2018)

9,965

6,222

Tax-exempt bonds, maturing through 2048, fixed and variable interest rates ranging from 1.35% to 4.3% (weighted average interest rate of 2.4% as of June 30, 2019 and 2.35% as of December 31, 2018)

2,294

2,388

Financing leases and other, maturing through 2056, interest rates up to 9%

563

467

Debt issuance costs, discounts and other

(83)

(52)

12,739

10,026

Current portion of long-term debt

116

432

$

12,623

$

9,594