Revenue Recognition

The majority of our revenue is derived from the sale of vehicle parts. 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):



	Three Months Ended
	March 31,
	2019		2018
North America	$	1,155,698	$	1,172,585
Europe	1,440,841		1,037,046
Specialty	352,556		350,674
Parts and services	2,949,095		2,560,305
Other	151,208		160,459
Total revenue	$	3,100,303	$	2,720,764

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, 2019	$	24,006
Additional warranty revenue deferred	10,875
Warranty revenue recognized	(9,370		)
Balance as of March 31, 2019	$	25,511

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 original equipment manufacturers ("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.

Revenue by Geographic Area

See Note 15, "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, with contemplation of any expected reversals in revenue. As of both March 31, 2019 and December 31, 2018, we recorded a refund liability and return asset for expected returns of $105 million and $56 million, respectively. 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 Unaudited Condensed Consolidated Balance Sheets. We recorded a reserve for our variable consideration of $66 million and $103 million as of March 31, 2019 and December 31, 2018, respectively. 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 unaudited condensed consolidated financial statements.