FAIR VALUE MEASUREMENTS

Accounting standards pertaining to fair value measurements establish a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.

As of June 30, 2018, the Company held certain items that are required to be measured at fair value on a recurring basis. These included cash equivalents, short-term investments (primarily treasury bills and certificates of deposit), interest rate derivative contracts, fuel derivative contracts, and available-for-sale securities. The majority of the Company’s short-term investments consist of instruments classified as Level 1. However, the Company has certificates of deposit, commercial paper, and time deposits that are classified as Level 2, due to the fact that the fair value for these instruments is determined utilizing observable inputs in non-active markets. Other available-for-sale securities primarily consist of investments associated with the Company’s excess benefit plan.

The Company’s fuel and interest rate derivative instruments consist of over-the-counter contracts, which are not traded on a public exchange. Fuel derivative instruments currently consist solely of option contracts, whereas interest rate derivatives consist solely of swap agreements. See Note 3 for further information on the Company’s derivative instruments and hedging activities. The fair values of swap contracts are determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets. Therefore, the Company has categorized these swap contracts as Level 2. The Company’s Treasury Department, which reports to the Chief Financial Officer, determines the value of option contracts utilizing an option pricing model based on inputs that are either readily available in public markets, can be derived from information available in publicly quoted markets, or are provided by financial institutions that trade these contracts. The option pricing model used by the Company is an industry standard model for valuing options and is the same model used by the broker/dealer community (i.e., the Company’s counterparties). The inputs to this option pricing model are the option strike price, underlying price, risk free rate of interest, time to expiration, and volatility. Because certain inputs used to determine the fair value of option contracts are unobservable (principally implied volatility), the Company has categorized these option contracts as Level 3. Volatility information is obtained from external sources, but is analyzed by the Company for reasonableness and compared to similar information received from other external sources. The fair value of option contracts considers both the intrinsic value and any remaining time value associated with those derivatives that have not yet settled. The Company also considers counterparty credit risk and its own credit risk in its determination of all estimated fair values. To validate the reasonableness of the Company’s option pricing model, on a monthly basis, the Company compares its option valuations to third party valuations. If any significant differences were to be noted, they would be researched in order to determine the reason. However, historically, no significant differences have been noted. The Company has consistently applied these valuation techniques in all periods presented and believes it has obtained the most accurate information available for the types of derivative contracts it holds.

Included in Other available-for-sale securities are the Company’s investments associated with its deferred compensation plans, which consist of mutual funds that are publicly traded and for which market prices are readily available. These plans are non-qualified deferred compensation plans designed to hold contributions in excess of limits established by the Internal Revenue Code of 1986, as amended. The distribution timing and payment amounts under these plans are made based on the participant’s distribution election and plan balance. Assets related to the funded portions of the deferred compensation plans are held in a rabbi trust, and the Company remains liable to these participants for the unfunded portion of the plans. The Company records changes in the fair value of the assets in the Company’s earnings.

The following tables present the Company’s assets and liabilities that are measured at fair value on a recurring basis at June 30, 2018, and December 31, 2017:



				Fair value measurements at reporting date using:
				Quoted prices in active markets for identical assets		Significant other observable inputs			Significant unobservable inputs
Description	June 30, 2018			(Level 1)		(Level 2)			(Level 3)
Assets	(in millions)
Cash equivalents
Cash equivalents (a)	$	1,595		$	1,595	$	—		$	—
Commercial paper	479			—		479			—
Certificates of deposit	15			—		15			—
Time deposits	25			—		25			—
Short-term investments:
Treasury bills	1,340			1,340		—			—
Certificates of deposit	232			—		232			—
Fuel derivatives:
Option contracts (b)	601			—		—			601
Other available-for-sale securities	128			128		—			—
Total assets	$	4,415		$	3,063	$	751		$	601
Liabilities
Fuel derivatives:
Option contracts (b)	(5		)	—		—			(5		)
Interest rate derivatives (see Note 3)	(24		)	—		(24		)	—
Total liabilities	$	(29	)	$	—	$	(24	)	$	(5	)

(a) Cash equivalents are primarily composed of money market investments.

(b) In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net asset. See Note 3.



				Fair value measurements at reporting date using:
				Quoted prices in active markets for identical assets		Significant other observable inputs			Significant unobservable inputs
Description	December 31, 2017			(Level 1)		(Level 2)			(Level 3)
Assets	(in millions)
Cash equivalents
Cash equivalents (a)	$	1,133		$	1,133	$	—		$	—
Commercial paper	350			—		350			—
Certificates of deposit	12			—		12			—
Short-term investments:
Treasury bills	1,491			1,491		—			—
Certificates of deposit	287			—		287			—
Fuel derivatives:
Option contracts (b)	283			—		—			283
Other available-for-sale securities	107			107		—			—
Total assets	$	3,663		$	2,731	$	649		$	283
Liabilities
Fuel derivatives:
Option contracts (b)	(35		)	—		—			(35		)
Interest rate derivatives (see Note 3)	(22		)	—		(22		)	—
Total liabilities	$	(57	)	$	—	$	(22	)	$	(35	)

(a) Cash equivalents are primarily composed of money market investments.

(b) In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net asset. See Note 3.

The Company had no transfers of assets or liabilities between any of the above levels during the six months ended June 30, 2018, or the year ended December 31, 2017. The Company did not have any assets or liabilities measured at fair value on a nonrecurring basis as of the six months ended June 30, 2018, or the year ended December 31, 2017. The following tables present the Company’s activity for items measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and six months ended June 30, 2018:



Fair value measurements using significant unobservable inputs (Level 3)
(in millions)	Fuel derivatives
Balance at March 31, 2018	$	340
Total gains (realized or unrealized) included in other comprehensive income	298
Purchases	9			(a)
Sales	(2		)	(a)
Settlements	(49		)
Balance at June 30, 2018	$	596

(a) The purchase and sale of fuel derivatives are recorded gross based on the structure of the derivative instrument and whether a contract with multiple derivatives is purchased as a single instrument or separate instruments.



Fair value measurements using significant unobservable inputs (Level 3)
(in millions)	Fuel derivatives
Balance at December 31, 2017	$	248
Total gains (realized or unrealized) included in other comprehensive income	399
Purchases	27			(a)
Sales	(2		)	(a)
Settlements	(76		)
Balance at June 30, 2018	$	596

The significant unobservable input used in the fair value measurement of the Company’s derivative option contracts is implied volatility. Holding other inputs constant, an increase (decrease) in implied volatility would result in a higher (lower) fair value measurement, respectively, for the Company’s derivative option contracts.

The following table presents a range of the unobservable inputs utilized in the fair value measurements of the Company’s fuel derivatives classified as Level 3 at June 30, 2018:



Quantitative information about Level 3 fair value measurements
	Valuation technique	Unobservable input	Period (by year)	Range
Fuel derivatives	Option model	Implied volatility	Third quarter 2018	15-30%
			Fourth quarter 2018	22-31%
			2019	22-28%
			2020	21-26%
			2021	20-22%
			2022	19-20%

The carrying amounts and estimated fair values of the Company’s long-term debt (including current maturities), as well as the applicable fair value hierarchy tier, at June 30, 2018, are presented in the table below. The fair values of the Company’s publicly held long-term debt are determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets; therefore, the Company has categorized these agreements as Level 2. Debt under five of the Company’s debt agreements is not publicly held. The Company has determined the estimated fair value of this debt to be Level 3, as certain inputs used to determine the fair value of these agreements are unobservable. The Company utilizes indicative pricing from counterparties and a discounted cash flow method to estimate the fair value of the Level 3 items.



(in millions)	Carrying value		Estimated fair value		Fair value level hierarchy
2.75% Notes due 2019	$	298	$	297	Level 2
Term Loan Agreement payable through 2019 - 6.315%	44		45		Level 3
Term Loan Agreement payable through 2019 - 4.84%	15		15		Level 3
2.65% Notes due 2020	486		480		Level 2
Term Loan Agreement payable through 2020 - 5.223%	212		212		Level 3
737 Aircraft Notes payable through 2020	121		121		Level 3
2.75% Notes due 2022	300		292		Level 2
Pass Through Certificates due 2022 - 6.24%	273		289		Level 2
Term Loan Agreement payable through 2026 - 3.62%	206		206		Level 3
3.00% Notes due 2026	300		277		Level 2
3.45% Notes due 2027	300		284		Level 2
7.375% Debentures due 2027	126		148		Level 2