Debt

Debt with a contractual term less than one year is generally classified as short-term debt and consisted of the following as of December 31 (in thousands):



	2017		2016
Unsecured commercial paper	$	1,273,482	$	1,055,708
Total short-term debt	$	1,273,482	$	1,055,708

Debt with a contractual term greater than one year is generally classified as long-term debt and consisted of the following as of December 31 (in thousands):



	2017			2016
Secured debt (Note 10)
Asset-backed Canadian commercial paper conduit facility	$	174,779		$	149,338
Asset-backed U.S. commercial paper conduit facilities	279,457			—
Asset-backed securitization debt	353,085			797,755
Less: unamortized discount and debt issuance costs	(461		)	(1,480		)
Total secured debt	806,860			945,613

Unsecured notes (at par value)
2.70% Medium-term notes due in 2017, issued January 2012	—			400,000
1.55% Medium-term notes due in 2017, issued November 2014	—			400,000
6.80% Medium-term notes due in 2018, issued May 2008	877,488			877,488
2.25% Medium-term notes due in 2019, issued January 2016	600,000			600,000
Floating-rate Medium-term notes due in 2019, issued March 2017^(a)	150,000			—
2.40% Medium-term notes due in 2019, issued September 2014	600,000			600,000
2.15% Medium-term notes due in 2020, issued February 2015	600,000			600,000
2.40% Medium-term notes due in 2020, issued March 2017	350,000			—
2.85% Medium-term notes due in 2021, issued January 2016	600,000			600,000
2.55% Medium-term notes due in 2022, issued June 2017	400,000			—
3.50% Senior unsecured notes due in 2025, issued July 2015	450,000			450,000
4.625% Senior unsecured notes due in 2045, issued July 2015	300,000			300,000
Less: unamortized discount and debt issuance costs	(19,821		)	(21,242		)
Gross long-term debt	5,714,527			5,751,859
Less: current portion of long-term debt, net of unamortized discount and issuance costs	(1,127,269		)	(1,084,884		)
Total long-term debt	$	4,587,258		$	4,666,975

(a) Floating interest rate based on LIBOR plus 35 bps.

A summary of the Company’s expected principal payments for debt obligations as of December 31, 2017 is as follows (in thousands):



2018	$	2,405,569
2019	1,594,518
2020	1,098,489
2021	721,705
2022	438,010
Thereafter	750,000
Total	$	7,008,291

Commercial paper maturities may range up to 365 days from the issuance date. The weighted-average interest rate of outstanding commercial paper balances was 1.48% and 0.93% at December 31, 2017 and 2016, respectively.

In May 2017, the Company entered into a $100.0 million 364-day credit facility which matures in April 2018. The Company also has a $675.0 million five-year credit facility which matures in April 2019 and a $765.0 million five-year credit facility which matures in April 2021. The new 364-day credit facility and the five-year credit facilities (together, the Global Credit Facilities) bear interest at variable interest rates, which may be adjusted upward or downward depending on certain criteria, such as credit ratings. The Global Credit Facilities also require the Company to pay a fee based on the average daily unused portion of the aggregate commitments under the Global Credit Facilities. The Global Credit Facilities are committed facilities and primarily used to support the Company's unsecured commercial paper program. Additionally, during the second quarter of 2017, the Company renewed its $25.0 million credit facility which expired in May 2017. The $25.0 million credit facility bears interest at variable interest rates, and the Company must pay a fee based on the unused portion of the $25.0 million commitment. The credit facility expires in May 2018.

All of the Company's unsecured notes provide for semi-annual interest payments and principal due at maturity.

During 2017, the Company did not repurchase any of its medium-term notes. During 2016 and 2015, the Company repurchased an aggregate of $1.2 million and $9.3 million, respectively, of its 6.80% medium-term notes which mature in June 2018. As a result, the Company recognized in financial services interest expense $0.1 million and $1.1 million of loss on extinguishment of debt, respectively, which included unamortized discounts and fees. During March and November 2017, $400.0 million of 2.70% and $400.0 million of 1.55% medium-term notes matured, respectively, and the principal and accrued interest were paid in full.

HDFS and the Company are subject to various operating and financial covenants related to the credit facilities and various operating covenants under the Notes and the U.S. and Canadian asset-backed commercial paper conduit facilities. The more significant covenants are described below.

The operating covenants limit the Company’s and HDFS’ ability to:


•	Assume or incur certain liens;


•	Participate in certain mergers or consolidations; and


•	Purchase or hold margin stock.

Under the current financial covenants of the Global Credit Facilities, the consolidated debt to equity ratio of HDFS cannot exceed 10.00 to 1.00 as of the end of any fiscal quarter. In addition, the ratio of the Company's consolidated debt to the Company's consolidated debt and equity, in each case excluding the debt of HDFS and its subsidiaries, cannot exceed 0.70 to 1.00 as of the end of any fiscal quarter. No financial covenants are required under the Notes or the U.S. or Canadian asset-backed commercial paper conduit facilities. At December 31, 2017 and 2016, HDFS and the Company remained in compliance with all of these covenants.