Fair Value Measurements

Financial Assets and Liabilities

The following fair value hierarchy table presents information about the Company's financial assets and liabilities measured at fair value on a recurring basis:



(In thousands)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Balance at December 31, 2017
Assets
Deferred compensation plan	$	14,966	$	—	$	—	$	14,966
Derivative instruments	—		—		2,239		2,239
Total assets	$	14,966	$	—	$	2,239	$	17,205
Liabilities
Deferred compensation plan	$	29,145	$	—	$	—	$	29,145
Derivative instruments	—		—		30,637		30,637
Total liabilities	$	29,145	$	—	$	30,637	$	59,782



(In thousands)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Balance at December 31, 2016
Assets
Deferred compensation plan	$	12,587	$	—	$	—	$	12,587
Derivative instruments	—		—		2,991		2,991
Total assets	$	12,587	$	—	$	2,991	$	15,578
Liabilities
Deferred compensation plan	$	24,169	$	—	$	—	$	24,169
Derivative instruments	—		21,400		18,859		40,259
Total liabilities	$	24,169	$	21,400	$	18,859	$	64,428

The Company's investments associated with its deferred compensation plan consist of mutual funds and deferred shares of the Company's common stock that are publicly traded and for which market prices are readily available.

The derivative instruments were measured based on quotes from the Company's counterparties or internal models. Such quotes and models have been derived using an income approach that considers various inputs including current market and contractual prices for the underlying instruments, quoted forward prices for natural gas and crude oil, basis differentials, volatility factors and interest rates, such as a LIBOR curve for a similar length of time as the derivative contract term as applicable. Estimates are derived from or verified using relevant NYMEX futures contracts and/or are compared to multiple quotes obtained from counterparties for reasonableness. The determination of the fair values presented above also incorporates a credit adjustment for non-performance risk. The Company measured the non-performance risk of its counterparties by reviewing credit default swap spreads for the various financial institutions with which it has derivative transactions while non-performance risk of the Company is evaluated using a market credit spread provided by the Company's bank. The Company has not incurred any losses related to non-performance risk of its counterparties and does not anticipate any material impact on its financial results due to non-performance by third parties.

The most significant unobservable inputs relative to the Company's Level 3 derivative contracts are basis differentials and volatility factors. An increase (decrease) in these unobservable inputs would result in an increase (decrease) in fair value, respectively. The Company does not have access to the specific assumptions used in its counterparties' valuation models. Consequently, additional disclosures regarding significant Level 3 unobservable inputs were not provided.

The following table sets forth a reconciliation of changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy:



	Year Ended December 31,
(In thousands)	2017			2016			2015
Balance at beginning of period	$	(15,868	)	$	—		$	85,958
Total gain (loss) included in earnings	(1,866		)	(17,886		)	32,864
Settlement (gain) loss	(10,664		)	2,018			(118,822		)
Balance at end of period	$	(28,398	)	$	(15,868	)	$	—

Change in unrealized gains (losses) relating to assets and liabilities still held at the end of the period	$	(28,398	)	$	(15,868	)	$	—

There were no transfers between Level 1 and Level 2 fair value measurements for the years ended December 31, 2017, 2016 and 2015.

Non-Financial Assets and Liabilities

The Company discloses or recognizes its non-financial assets and liabilities, such as impairments of oil and gas properties or other than temporary impairments of equity method investments, at fair value on a nonrecurring basis. The Company recorded an impairment charge related to certain oil and gas properties and other assets during the years ended December 31, 2017, 2016 and 2015. The Company also recorded an other than temporary impairment of its equity method investment in Constitution during the year ended December 31, 2017. Refer to Notes 3 and 4 for additional disclosures related to fair value associated with the impaired assets. As none of the Company’s other non-financial assets and liabilities were measured at fair value as of December 31, 2017, 2016 and 2015, additional disclosures were not required.

The estimated fair value of the Company's asset retirement obligation at inception is determined by utilizing the income approach by applying a credit-adjusted risk-free rate, which takes into account the Company's credit risk, the time value of money, and the current economic state to the undiscounted expected abandonment cash flows. Given the unobservable nature of the inputs, the measurement of the asset retirement obligations was classified as Level 3 in the fair value hierarchy.

Fair Value of Other Financial Instruments

The estimated fair value of other financial instruments is the amount at which the instrument could be exchanged currently between willing parties. The carrying amount reported in the Consolidated Balance Sheet for cash and cash equivalents approximates fair value due to the short-term maturities of these instruments. Cash and cash equivalents are classified as Level 1 in the fair value hierarchy and the remaining financial instruments are classified as Level 2.

The Company uses available market data and valuation methodologies to estimate the fair value of debt. The fair value of debt is the estimated amount the Company would have to pay a third party to assume the debt, including a credit spread for the difference between the issue rate and the period end market rate. The credit spread is the Company's default or repayment risk. The credit spread (premium or discount) is determined by comparing the Company's senior notes and revolving credit facility to new issuances (secured and unsecured) and secondary trades of similar size and credit statistics for both public and private debt. The fair value of all senior notes and the revolving credit facility is based on interest rates currently available to the Company. The Company's debt is valued using an income approach and classified as Level 3 in the fair value hierarchy.

The carrying amount and fair value of debt is as follows:



	December 31, 2017						December 31, 2016
(In thousands)	Carrying Amount			Estimated Fair Value			Carrying Amount		Estimated Fair Value
Long-term debt	$	1,521,891		$	1,527,624		$	1,520,530	$	1,463,643
Current maturities	(304,000		)	(312,055		)	—		—
Long-term debt, excluding current maturities	$	1,217,891		$	1,215,569		$	1,520,530	$	1,463,643