6. DEBT

Short-Term Debt

At March 31, 2017, we had no outstanding short-term debt.

Long-Term Debt

At March 31, 2017, we had long-term debt of $719.7 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 2017 through 2046, interest rates ranging from 1.545% to 9.05%, and a weighted-average coupon rate of 5.083%.

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 2016 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	2017			2016			2016
Gross long-term debt	$	726,700		$	601,700		$	726,700
Unamortized debt issuance costs	(6,990		)	(6,975		)	(7,377		)
Carrying amount	$	719,710		$	594,725		$	719,323
Estimated fair value⁽¹⁾	785,980			686,159			793,339

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