(5) Commitments and Contingencies

Lease Obligations

The Company leases 470 aircraft, as well as airport facilities, office space, and various other property and equipment under non‑cancelable operating leases which are generally on a long‑term net rent basis where the Company pays taxes, maintenance, insurance and certain other operating expenses applicable to the leased property. The following table summarizes future minimum rental payments required under operating leases that have non‑cancelable lease terms as of December 31, 2015 (in thousands):


Year ended December 31,
2016	$	269,520
2017		192,122
2018		154,077
2019		121,107
2020		133,659
Thereafter		349,038
	$	1,219,523

The majority of the Company’s leased aircraft are owned and leased through trusts whose sole purpose is to purchase, finance and lease these aircraft to the Company; therefore, they meet the criteria of a variable interest entity. However, since these are single owner trusts in which the Company does not participate, the Company is not considered at risk for losses and is not considered the primary beneficiary. As a result, based on the current rules, the Company is not required to consolidate any of these trusts or any other entities in applying the accounting guidance. The Company’s management believes that the Company’s maximum exposure under these leases is the remaining lease payments.

The Company’s leveraged lease agreements typically obligate the Company to indemnify the equity/owner participant against liabilities that may arise due to changes in benefits from tax ownership of the respective leased aircraft. The terms of these contracts range up to 11 years. The Company did not accrue any liability relating to the indemnification to the equity/owner participant because of management’s assessment that the probability of this occurring is remote.

During the year ended December 31, 2015, the Company built a maintenance facility in Boise, Idaho and entered into a sale lease-back agreement with the city of Boise. The sales price of the facility was $18.5 million and the operating lease expires in 2040. The future lease obligations for the Boise maintenance facility are included in the above future minimum rental payments schedule.

Total rental expense for non-cancelable aircraft operating leases was approximately $273.7 million, $305.3 million and $325.4 million for the years ended December 31, 2015, 2014 and 2013, respectively. The minimum rental expense for airport station rents was approximately $35.1 million, $29.0 million and $35.1 million for the years ended December 31, 2015, 2014 and 2013, respectively.

Self‑insurance

The Company self‑insures a portion of its potential losses from claims related to workers’ compensation, environmental issues, property damage, medical insurance for employees and general liability. Losses are accrued based on an estimate of the ultimate aggregate liability for claims incurred, using standard industry practices and the Company’s actual experience. Actual results could differ from these estimates.

Legal Matters

The Company is subject to certain legal actions which it considers routine to its business activities. As of December 31, 2015, management believed, after consultation with legal counsel, that the ultimate outcome of such legal matters was not likely to have a material adverse effect on the Company’s financial position, liquidity or results of operations.

Concentration Risk and Significant Customers

The Company requires no collateral from its major partners or customers but monitors the financial condition of its major partners. Under the majority of the Company’s code-share agreements, the Company receives weekly payments from its major code share partners that approximates a significant percentage of the compensation earned for such period. Additionally, the Company provides certain customer service functions at multiple airports for various airlines and the Company maintains an allowance for doubtful accounts receivable based upon expected collectability of all accounts receivable. The Company’s allowance for doubtful accounts totaled $187,300 and $326,600 as of December 31, 2015 and 2014, respectively. For the years ended December 31, 2015, 2014 and 2013, the Company’s contractual relationships with Delta and United combined accounted for approximately 86.9%, 88.7% and 91.6%, respectively of the Company’s total revenues.

Employees Under Collective Bargaining Agreements

As of December 31, 2015, the Company had approximately 18,300 full‑time equivalent employees. Approximately 38.0% of these employees were represented by unions, including the following employee groups. Notwithstanding the completion of the ExpressJet Combination, ExpressJet’s employee groups continue to be represented by those unions who provided representation prior to the ExpressJet Combination.

Accordingly, the following table refers to ExpressJet’s employee groups based upon their union affiliations prior to the ExpressJet Combination.


	Approximate
	Number of
	Active Employees		Status of
Employee Group	Represented	Representatives	Agreement
Atlantic Southeast Pilots	1,491	Air Line Pilots Association International	Amendable February 2018
Atlantic Southeast Flight Attendants	1,031	International Association of Machinists and Aerospace Workers	Amendable
Atlantic Southeast Flight Controllers	36	Transport Workers Union of America	Amendable
Atlantic Southeast Mechanics	364	International Brotherhood of Teamsters	Amendable
Atlantic Southeast Stock Clerks	73	International Brotherhood of Teamsters	Amendable
ExpressJet Delaware Pilots	2,107	Air Line Pilots Association International	Amendable February 2018
ExpressJet Delaware Flight Attendants	993	International Association of Machinists and Aerospace Workers	Amendable
ExpressJet Delaware Mechanics	711	International Brotherhood of Teamsters	Amendable
ExpressJet Delaware Dispatchers	53	Transport Workers Union of America	Amendable
ExpressJet Delaware Stock Clerks	96	International Brotherhood of Teamsters	Amendable

In February 2016, the Atlantic Southeast Pilots and the ExpressJet Delaware Pilots ratified a two-year contract extension to their respective labor agreements.