In 2014, the Financial Accounting Standard Board ("the FASB") issued ASC 606, Revenue from Contracts with Customers (“ASC 606”), replacing the existing accounting standard and industry specific guidance for revenue recognition with a five-step model for recognizing and measuring revenue from contracts with customers. The underlying principle of the new standard is to recognize revenue to depict the transfer of goods or services to customers at the amount expected to be collected. ASC 606 became effective on January 1, 2018 and we adopted it using the modified retrospective method applied to open contracts and only to the version of the contracts in effect as of January 1, 2018. There was no impact on the condensed consolidated financial statements and no cumulative effect adjustment was recognized.

In general, under ASC 606, we recognize revenue when a service or good is sold to a customer and a contract exists. At contract inception, we assess the goods and services promised in our contracts with customers and identify all performance obligations for each distinct promise that transfers a good or service (or bundle of goods or services) to the customer. To identify the performance obligations, we consider all goods or services promised in the contract, whether explicitly stated or implied based on customary business practices. Revenue is recognized when control of the identified distinct goods or services has been transferred to the customer, the transaction price has been determined and allocated to the performed performance obligations and we have determined that collection has occurred or is probable of occurring.

Taxes billed to and collected from customers and remitted to governmental authorities are reported as revenue on a net basis in our financial statements. Thus, we exclude taxes billed to the customer and collected on behalf of governmental agencies to be remitted to these agencies from the transaction price in determining the revenue related to contracts with a customer.

Oil & Gas Revenue Recognition - We provide helicopter services to oil and gas customers operating in the Gulf of Mexico and a number of foreign countries. Revenues are recognized when performance obligations are satisfied over time in accordance with contractual terms, in an amount that reflects the consideration the Company expects to be entitled to in exchange for services rendered.

Air Medical Revenue Recognition - We provide helicopter services to hospitals and emergency service providers in several U.S. states, or to individual patients in the U.S. in which case we are paid by either a commercial insurance company, federal or state agency, or the patient. Our Air Medical segment operates primarily under the independent provider model and, to a lesser extent, under the traditional provider model. Revenues related to the independent provider model services are recorded in the period in which we satisfy our performance obligations under contracts by providing our services to our customers based upon established billing rates net of contractual allowances under agreements with third party payors and net of uncompensated care allowances. These amounts are due from patients, third-party payors (including health insurers and government programs), and others and includes variable consideration for retroactive revenue adjustments due to settlement of audits, reviews, and investigations. Generally, we bill the patients and third-party payors several days after the services are performed. Revenues generated under the traditional provider model are recognized as performance obligations are satisfied over time in accordance with contractual terms, in an amount that reflects the consideration the Company expects to be entitled in exchange for services rendered.

Oil & Gas Performance Obligations - A performance obligation arises under contracts with customers to render services and is the unit of account under ASC 606. Operating revenue from our Oil and Gas segment is derived mainly from fixed-term contracts with our customers, a substantial portion of which are competitively bid. A small portion of our Oil and Gas segment revenue is derived from providing services on an "ad-hoc" basis. Our fixed-term contracts typically have original terms of one to seven years (subject to provisions permitting early termination on relatively short notice by the customers). We account for services rendered separately if they are distinct and the services are separately identifiable from other items provided to a customer and if a customer can benefit from the services rendered on its own or with other resources that are readily available to the customer. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. Within this contract type for helicopter services, we determined that each contract has a single distinct performance obligation. These services include a fixed monthly rate for a particular model of aircraft, and flight hour services, which represents the variable component of a typical contract with a customer. Rates for these services vary depending on the type of services provided and can be based on a per flight hour, per day, or per month basis. We also provide services to clients on an “ad hoc” basis, which usually entails a shorter contract notice period and duration. The charges for ad hoc services are based on an hourly rate or a daily or monthly fixed fee plus additional fees for each hour flown. The nature of our variable charges within our flight services contracts are not effective until a customer-initiated flight order and the actual hours flown are determined; therefore, the associated flight revenue generally cannot be reasonably and reliably estimated before hand. A contract’s standalone selling prices are determined based upon the prices that we charge for our services rendered. The majority of our revenue is recognized as performance obligations satisfied over time, by measuring progress towards satisfying the contracted services in a manner that best depicts the transfer of services to the customer, which is generally represented by a period of 30 days or less. We typically invoice customers on a monthly basis with the term between invoicing and when the payment is due typically being between 30 and 60 days.

Air Medical Performance Obligations - Performance obligations are determined based upon the nature of the services provided. Under the independent provider model, we measure the performance obligation from the moment the patient is loaded into the aircraft until it reaches its destination. Under this model, we have no fixed revenue stream and compete for transport referrals on a daily basis with other independent operators in the area. Under the traditional provider model, we contract directly with the customer to provide their transportation services. These contracts are typically awarded or renewed through competitive bidding and typically permit early termination by the customer on relatively short notice. As a traditional provider, we typically bill a fixed monthly rate for aircraft availability and an hourly rate for flight time. For each of these types of helicopter services, we have determined that each has a single distinct performance obligation. Traditional provider models services include fixed monthly rate for a particular model of aircraft, and flight hour services, which represents the variable component of a typical contract with a customer. Rates for these services vary depending on the type of services provided and can be based on a per flight hour, per day, or per month basis. The variable charges within such contracts are not effective until the customer initiates a flight order and the actual hours flown are determined; therefore, the associated revenue generally cannot be reasonably and reliably estimated beforehand. For the traditional provider model, we determine the transaction price based upon standard charges for goods and services provided.

As an independent provider, we bill for our services on the basis of a flat rate plus a variable charge per patient-loaded mile, regardless of aircraft model, and are typically compensated by private insurance, Medicaid or Medicare, or directly by transported patients who self-pay. We recognize revenues for performance obligations satisfied at a point in time, which generally relate to patients receiving air medical services when: (1) services are provided; and (2) we do not believe the patient requires additional services. For the independent provider model, we determine the transaction price based upon gross charges for services provided reduced by contractual adjustments provided to third-party payors, discounts provided to uninsured patients in accordance with Company policy, and/or implicit price concessions provided to uninsured patients. We determine estimates of contractual adjustments and discounts based upon contractual agreements, our discount policy, and historical experience. We determine our estimate of implicit price concessions based upon our historical collection experience with these classes of patients using a portfolio approach as a practical expedient to account for patient contracts as collective groups, rather than individually. The financial statement effects of using this practical expedient are not materially different from an individual contract approach.

We estimate contractual allowances and uncompensated care based on historical collection experience by payor category. The main payor categories are Medicaid, Medicare, private insurance, and self-pay. Changes in payor mix, reimbursement rates and uncompensated care rates are the factors most subject to sensitivity and variability in calculating our allowances. We compute a historical payment analysis of accounts by category. The allowance percentages calculated are applied to the payor categories, and the necessary adjustments are made to the revenue allowance. In our Air Medical Segment, the allowance for contractual discounts against outstanding accounts receivable was $140.5 million, and $123.8 million as of June 30, 2019, and December 31, 2018, respectively, and the allowance for uncompensated care against outstanding accounts receivable was $45.5 million, and $51.9 million as of June 30, 2019 and December 31, 2018, respectively. Included in the allowance for uncompensated care above is the value of services to patients who are unable to pay when it is determined that they qualify as charity care. The value of these services was $1.6 million, and $1.7 million for the quarter ended on June 30, 2019 and 2018, respectively. The value of these services was $3.5 million and $3.3 million for the six months ended June 30, 2019 and 2018, respectively. The estimated cost of providing charity services was $0.3 million and $0.4 million for the quarters ended June 30, 2019 and 2018, respectively. The estimated cost of providing charity services was $0.8 million for the six months ended June 30, 2019 and 2018, respectively. The estimated costs of providing charity services are based on a calculation that applies a ratio of costs to the charges for uncompensated charity care. The ratio of costs to charges is based on the Air Medical independent provider model’s total expenses divided by gross patient service revenue.

In determining the allowance estimates for our Air Medical segment’s billing, receivables and revenue, we utilize the prior twelve months’ payment history and current trends in payor behavior by each separate payor group, which we evaluate on a state by state basis. A percentage of amounts collected compared to the total invoice is determined from this process and applied to the current month’s billings and receivables. If a receivable related to the self-pay category is outstanding twelve months or greater, we record a reserve equal to 100% of the receivable. Receivables related to other payor categories are scrutinized when they are outstanding for nine months or longer and additional allowances are recorded if warranted.

As of June 30, 2019 and December 31, 2018, net receivables related to our (i) Oil and Gas segment were $86.2 million and $74.1 million, (ii) Air Medical segment were $95.8 million and $90.2 million and (iii) Technical Services segment were $1.3 million and $4.1 million, respectively.

We generally have a right to consideration in an amount that corresponds directly with the value to the customer of the entity's performance completed to date and may recognize revenue in the amount to which the entity has a right to invoice. We have elected to use the invoice practical expedient for revenue recognized when performance obligations are satisfied over time. In addition, payment for goods and services rendered is typically due in the subsequent month following satisfaction of our performance obligation. Our contracts typically include termination clauses that allow both parties to terminate existing contracts with a 30 to 180 day notice period.

Our Technical Services segment - provides helicopter flight services and helicopter repair and overhaul services for existing flight operations customers that own their own aircraft. Under this segment, we periodically provide certain services to governmental customers, including our agreement to operate six aircraft for the National Science Foundation in Antarctica. Under this segment, we also offer certain software as a service to our Oil and Gas customers. Revenues are recognized when performance obligations are satisfied in accordance with contractual terms, in an amount that reflects the consideration we expect to be entitled to in exchange for services rendered. For these helicopter services, we determined that each has a single distinct performance obligation.

The following table presents the Company’s revenues by segment disaggregated by type (in thousands):

	For the Quarter Ended June 30,				For the Six Months Ended June 30,
	2019		2018		2019		2018
Service Revenue
Oil & Gas	$	90,023	$	97,068	$	174,969	$	192,702
Air Medical		69,507		67,151		126,153		124,139
Technical Services		5,642		5,024		15,940		12,766
Total Services	$	165,172	$	169,243	$	317,062	$	329,607

Air Medical Revenue
Traditional provider model	$	12,401	$	12,085	$	24,378	$	23,956
Independent provider model		57,106		55,066		101,775		100,183
Total Air Medical Revenues	$	69,507	$	67,151	$	126,153	$	124,139