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 December 31, 2017, 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 and commercial paper 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 include swaps, as well as different types of option contracts, whereas interest rate derivatives consist solely of swap agreements. See Note 10 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 December 31, 2017, and December 31, 2016:



				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 10)	(22		)	—		(22		)	—
Total liabilities	$	(57	)	$	—	$	(22	)	$	(35	)

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

(b) In the Consolidated Balance Sheet amounts are presented as a net asset. See Note 10.



				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, 2016			(Level 1)		(Level 2)			(Level 3)
Assets	(in millions)
Cash equivalents
Cash equivalents (a)	$	1,344		$	1,344	$	—		$	—
Commercial paper	325			—		325			—
Certificates of deposit	11			—		11			—
Short-term investments:
Treasury bills	1,345			1,345		—			—
Certificates of deposit	280			—		280			—
Fuel derivatives:
Swap contracts (c)	42			—		42			—
Option contracts (b)	239			—		—			239
Option contracts (c)	163			—		—			163
Other available-for-sale securities	83			83		—			—
Total assets	$	3,832		$	2,772	$	658		$	402
Liabilities
Fuel derivatives:
Swap contracts (c)	$	(110	)	$	—	$	(110	)	$	—
Option contracts (b)	(96		)	—		—			(96		)
Option contracts (c)	(564		)	—		—			(564		)
Interest rate derivatives (see Note 10)	(35		)	—		(35		)	—
Total liabilities	$	(805	)	$	—	$	(145	)	$	(660	)

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

(b) In the Consolidated Balance Sheet amounts are presented as a net asset. See Note 10.

The Company had no transfers of assets or liabilities between any of the above levels during the years ended December 31, 2017 or 2016. The Company did not have any assets or liabilities measured at fair value on a nonrecurring basis as of December 31, 2017 or 2016. 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 2017 and 2016:



Fair value measurements using significant unobservable inputs (Level 3)
	Fuel
(in millions)	derivatives
Balance at December 31, 2016	$	(258	)
Total losses (realized or unrealized)
Included in earnings	(125		)
Included in other comprehensive income	(50		)
Purchases	142			(a)
Sales	—			(a)
Settlements	539
Balance at December 31, 2017	$	248
The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2017	$	(42	)

(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)
	Fuel				Other
(in millions)	derivatives				securities			Total
Balance at December 31, 2015	$	(1,676	)		$	27		$	(1,649	)
Total gains (losses) (realized or unrealized)
Included in earnings	175				(2		)	173
Included in other comprehensive income	201				8			209
Purchases	221			(a)	—			221
Sales	(61		)	(a)	(33		)	(94		)
Settlements	882				—			882
Balance at December 31, 2016	$	(258	)		$	—		$	(258	)
The amount of total gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2016	$	93			$	—		$	93

(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.

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 December 31, 2017:



Quantitative information about Level 3 fair value measurements
	Valuation technique	Unobservable input	Period (by year)	Range
Fuel derivatives	Option model	Implied volatility	2018	11-26%
			2019	17-22%
			2020	17-21%
			Beyond 2020	18-20%

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 December 31, 2017, 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 seven 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
French Credit Agreements due 2018 - 2.54%	$	1	$	1	Level 3
Fixed-rate 737 Aircraft Notes payable through 2018 - 7.03%	3		3		Level 3
2.75% Notes due 2019	300		302		Level 2
Term Loan Agreement payable through 2019 - 6.315%	66		66		Level 3
Term Loan Agreement payable through 2019 - 4.84%	19		20		Level 3
2.65% Notes due 2020	491		494		Level 2
Term Loan Agreement payable through 2020 - 5.223%	237		240		Level 3
737 Aircraft Notes payable through 2020	155		154		Level 3
2.75% Notes due 2022	300		300		Level 2
Pass Through Certificates due 2022 - 6.24%	294		318		Level 2
Term Loan Agreement payable through 2026 - 2.67%	215		215		Level 3
3.00% Notes due 2026	300		293		Level 2
3.45% Notes due 2027	300		299		Level 2
7.375% Debentures due 2027	127		154		Level 2