SHORT-TERM DEBT

Short-term debt consisted of the following (in millions of dollars):



	As of December 31,
	2018			2017
Lines of Credit
Outstanding at December 31	$	49		$	56
Maximum month-end balance during the year	$	138		$	56
Weighted average interest rate during the year	2.29		%	2.41		%
Weighted average interest rate at December 31	2.35		%	2.01		%

Commercial Paper
Outstanding at December 31	$	—		$	—
Maximum month-end balance during the year	$	90		$	455
Weighted average interest rate during the year	1.80		%	0.83		%

Lines of Credit

The Company's U.S. business has a five-year $750 million unsecured revolving line of credit, maturing in 2022. There were no borrowings outstanding under the line of credit as of December 31, 2018 and 2017. The primary purpose of this credit facility is to provide support to the Company's commercial paper program and for general corporate purposes.

Foreign subsidiaries utilize lines of credit for working capital purposes and other operating needs. These foreign lines of credit in aggregate were $49 million and $56 million as of December 31, 2018 and 2017, respectively.

Commercial Paper

The Company issues commercial paper from time to time for general working capital needs. At December 31, 2018, there was none outstanding.

The Company's short-term debt instruments include affirmative and negative covenants that are usual and customary for companies with similar credit ratings and do not contain any financial performance covenants. The Company was in compliance with all debt covenants as of December 31, 2018.