SHORT AND LONG-TERM DEBT

Short-term Debt

As a source of short-term financing, we utilize cash on hand and commercial paper or bank loans with an original maturity of three months or less. We maintain a $1.0 billion unsecured revolving credit facility, which currently expires in November 2020. This agreement also includes an option to increase borrowings by an additional $400,000 with the consent of the lenders. On June 16, 2016, we entered into an additional unsecured revolving credit facility that provided for borrowings up to $500,000. We terminated this facility, which was scheduled to expire on June 15, 2017, effective October 24, 2016.

The unsecured committed revolving credit agreement contains a financial covenant whereby the ratio of (a) pre-tax income from operations from the most recent four fiscal quarters to (b) consolidated interest expense for the most recent four fiscal quarters may not be less than 2.0 to 1.0 at the end of each fiscal quarter. The credit agreement also contains customary representations, warranties and events of default. Payment of outstanding advances may be accelerated, at the option of the lenders, should we default in our obligation under the credit agreement. As of December 31, 2016, we complied with all customary affirmative and negative covenants and the financial covenant pertaining to our credit agreement. There were no significant compensating balance agreements that legally restricted these funds.

In addition to the revolving credit facility, we maintain lines of credit with domestic and international commercial banks. Our credit limit in various currencies was $504,237 at December 31, 2016 and $516,916 at December 31, 2015. These lines permit us to borrow at the respective banks’ prime commercial interest rates, or lower. We had short-term foreign bank loans against these lines of credit for $158,805 at December 31, 2016 and $313,520 at December 31, 2015. Commitment fees relating to our revolving credit facility and lines of credit are not material.

At December 31, 2016, we had outstanding commercial paper totaling $473,666, at a weighted average interest rate of 0.6%. At December 31, 2015, we had outstanding commercial paper totaling $49,993, at a weighted average interest rate of 0.4%.

The maximum amount of short-term borrowings outstanding during 2016 was $997,120. The weighted-average interest rate on short-term borrowings outstanding was 1.0% as of December 31, 2016 and 3.0% as of December 31, 2015.

Long-term Debt

Long-term debt consisted of the following:



December 31,	2016			2015
5.45% Notes due 2016	$	—		$	250,000
1.50% Notes due 2016	—			250,000
1.60% Notes due 2018	300,000			300,000
4.125% Notes due 2020	350,000			350,000
8.8% Debentures due 2021	84,715			84,715
2.625% Notes due 2023	250,000			250,000
3.20% Notes due 2025	300,000			300,000
2.30% Notes due 2026	500,000			—
7.2% Debentures due 2027	193,639			193,639
3.375% Notes due 2046	300,000			—
Lease obligations	83,619			82,747
Net impact of interest rate swaps, debt issuance costs and unamortized debt discounts	(14,275		)	(4,087		)
Total long-term debt	2,347,698			2,057,014
Less—current portion	243			499,923
Long-term portion	$	2,347,455		$	1,557,091

In September 2016, we repaid $250,000 of 5.45% Notes due in 2016 upon their maturity. In November 2016, we repaid $250,000 of 1.50% Notes due in 2016 upon their maturity. In August 2016, we issued $500,000 of 2.30% Notes due in 2026 and $300,000 of 3.375% Notes due in 2046 (the "Notes"). Proceeds from the issuance of the Notes, net of discounts and issuance costs, totaled $792,953. The Notes were issued under a shelf registration statement on Form S-3 filed in June 2015 that registered an indeterminate amount of debt securities.

In August 2015, we paid $100,165 to repurchase $71,646 of our long-term debt as part of a cash tender offer, consisting of $15,285 of our 8.80% Debentures due in 2021 and $56,361 of our 7.20% Debentures due in 2027. We used a portion of the proceeds from the Notes issued in August 2015 to fund the repurchase. As a result of the repurchase, we recorded interest expense of $28,326 which represented the premium paid for the tender offer as well as the write-off of the related unamortized debt discount and debt issuance costs. Upon extinguishment of the debt, we unwound the fixed-to-floating interest rate swaps related to the tendered bonds and recognized a gain of $278 currently in interest expense resulting from the hedging instruments.

Aggregate annual maturities of long-term debt are as follows for the years ending December 31:



2017	$	243
2018	300,279
2019	367
2020	350,462
2021	85,279
Thereafter	1,611,068

Our debt is principally unsecured and of equal priority. None of our debt is convertible into our Common Stock.

Interest Expense

Net interest expense consisted of the following:



For the years ended December 31,	2016			2015			2014
Interest expense	$	97,851		$	93,520		$	93,777
Capitalized interest	(5,903		)	(12,537		)	(6,179		)
Loss on extinguishment of debt	—			28,326			—
Interest expense	91,948			109,309			87,598
Interest income	(1,805		)	(3,536		)	(4,066		)
Interest expense, net	$	90,143		$	105,773		$	83,532