6. DEBT

Short-Term Debt

At March 31, 2016, our short-term debt consisted of commercial paper notes payable with a maximum maturity of 43 days and an average maturity of 21 days and an outstanding balance of $164.9 million. The carrying cost of our commercial paper approximates fair value using Level 2 inputs, due to the short-term nature of the notes. See Note 2 in the 2015 Form 10-K for a description of the fair value hierarchy.

In the fourth quarter of 2015, we entered into a short-term credit facility loan totaling $50 million, as a short-term bridge through our peak heating season, which was repaid on February 4, 2016.

Long-Term Debt

At March 31, 2016, we had long-term debt of $594.7 million, which included $7.0 million of unamortized debt issuance costs. Utility long-term debt consists of first mortgage bonds (FMBs) with maturity dates ranging from 2016 through 2042, interest rates ranging from 3.176% to 9.05%, and a weighted-average coupon rate of 5.70%.

Fair Value of Long-Term Debt

Our outstanding debt does not trade in active markets. We estimate the fair value of our debt using utility companies with similar credit ratings, terms, and remaining maturities to our debt that actively trade in public markets. These valuations are based on Level 2 inputs as defined in the fair value hierarchy. See Note 2 in the 2015 Form 10-K for a description of the fair value hierarchy.

The following table provides an estimate of the fair value of our long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date:



	March 31,						December 31,
In thousands	2016			2015			2015
Gross long-term debt	$	601,700		$	661,700		$	601,700
Unamortized debt issuance costs	(6,975		)	(8,289		)	(7,282		)
Carrying amount	$	594,725		$	653,411		$	594,418
Estimated fair value⁽¹⁾	686,159			762,554			667,168


⁽¹⁾	Estimated fair value does not include unamortized debt issuance costs.