Revenue Recognition

The core principle of ASC 606 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. ASC 606 defines a five-step process to achieve this core principle, which includes:


1.	Identifying contracts with customers,


2.	Identifying performance obligations within those contracts,


3.	Determining the transaction price,


4.	Allocating the transaction price to the performance obligations in the contract, which may include an estimate of variable consideration, and


5.	Recognizing revenue when or as each performance obligation is satisfied.

The majority of our revenue is derived from the sale of vehicle parts. Under both the previous revenue standards and ASC 606, we recognize revenue when the products are shipped to, delivered to or picked up by customers, which is the point when title has transferred and risk of ownership has passed.

Sources of Revenue

We report our revenue in two categories: (i) parts and services and (ii) other. The following table sets forth our revenue by category, with our parts and services revenue further disaggregated by reportable segment (in thousands):



	Year Ended December 31,
	2018		2017		2016
North America	$	4,558,220	$	4,278,531	$	4,009,129
Europe	5,202,231		3,628,906		2,915,841
Specialty	1,472,956		1,301,197		1,219,675
Parts and services	11,233,407		9,208,634		8,144,645
Other	643,267		528,275		439,386
Total revenue	$	11,876,674	$	9,736,909	$	8,584,031

Parts and Services

Our parts revenue is generated from the sale of vehicle products including replacement parts, components and systems used in the repair and maintenance of vehicles and specialty products and accessories to improve the performance, functionality and appearance of vehicles. Services revenue includes additional services that are generally billed concurrently with the related product sales, such as the sale of service-type warranties and fees for admission to our self service yards.

In North America, our vehicle replacement products include sheet metal collision parts such as doors, hoods, and fenders; bumper covers; head and tail lamps; automotive glass products such as windshields; mirrors and grilles; wheels; and large mechanical items such as engines and transmissions. In Europe, our products include a wide variety of small mechanical products such as brake pads, discs and sensors; clutches; electrical products such as spark plugs and batteries; steering and suspension products; filters; and oil and automotive fluids. In our Specialty operations, we serve six product segments: truck and off-road; speed and performance; RV; towing; wheels, tires and performance handling; and miscellaneous accessories.

Our service-type warranties typically have service periods ranging from 6 months to 36 months. Under ASC 606, proceeds from these service-type warranties are deferred at contract inception and amortized on a straight-line basis to revenue over the contract period. The changes in deferred service-type warranty revenue are as follows (in thousands):



Balance as of January 1, 2018	$	19,465
Additional warranty revenue deferred	38,736
Warranty revenue recognized	(34,195		)
Balance as of December 31, 2018	$	24,006

Other Revenue

Revenue from other sources includes scrap sales, bulk sales to mechanical manufacturers (including cores) and sales of aluminum ingots and sows from our furnace operations. We derive scrap metal from several sources, including vehicles that have been used in both our wholesale and self service recycling operations and from OEMs and other entities that contract with us for secure disposal of "crush only" vehicles. The sale of hulks in our wholesale and self service recycling operations represents one performance obligation, and revenue is recognized based on a price per weight when the customer (processor) collects the scrap. Some adjustments may occur when the customer weighs the scrap at their location, and revenue is adjusted accordingly. We constrain our estimate of consideration to be received to the extent that we believe there will not be a significant reversal in revenue.

Revenue by Geographic Area

See Note 16, "Segment and Geographic Information" for information related to our revenue by geographic region.

Variable Consideration

The amount of revenue ultimately received from the customer can vary due to variable consideration which includes returns, discounts, rebates, refunds, credits, price concessions, incentives, performance bonuses, or other similar items. The previous revenue guidance required us to estimate the transaction price using a best estimate approach. Under ASC 606 we are required to select the “expected value method” or the “most likely amount” method in order to estimate variable consideration. We utilize both methods in practice depending on the type of variable consideration. In addition, our estimates of variable consideration are constrained to the extent that a significant reversal in revenue is not expected. We recorded a refund liability and return asset for expected returns of $105 million and $56 million, respectively, as of December 31, 2018 and a net reserve of $38 million as of December 31, 2017. The refund liability is presented separately on the balance sheet within current liabilities while the return asset is presented within prepaid expenses and other current assets. Other types of variable consideration consist primarily of discounts, volume rebates, and other customer sales incentives which are recorded in Receivables, net on the Consolidated Balance Sheets. We recorded a reserve for our variable consideration of $103 million and $78 million as of December 31, 2018 and December 31, 2017, respectively. Our May 2018 acquisition of Stahlgruber contributed $26 million to our variable consideration reserve; see Note 2, "Business Combinations" for further information on our acquisitions. While other customer incentive programs exist, we characterize them as material rights in the context of our sales transactions. We consider these programs to be immaterial to our consolidated financial statements.

Contract Costs

Under ASC 340, "Other Assets and Deferred Costs," we have elected to recognize incremental costs of obtaining a contract (commissions earned by our sales representatives on product sales) as an expense when incurred, as we believe the amortization period of the asset would be one year or less due to the short-term nature of our contracts.

Sales Taxes

We present taxes assessed by governmental authorities collected from customers on a net basis. Therefore, the taxes are excluded from revenue on our Consolidated Statements of Income and are shown as a current liability on our Consolidated Balance Sheets until remitted.