Revenue Recognition	6 Months Ended
Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Note 2. Revenue Recognition We generate our revenue through contracts with customers that primarily consist of hospitals, healthcare institutions, distributors and other organizations. Revenue is measured based on consideration specified in a contract with a customer, and excludes amounts collected on behalf of third parties. We measure the consideration based upon the estimated amount to be received. The amount of consideration we ultimately receive varies depending upon the return terms, sales rebates, discounts, and other incentives that we may offer, which are accounted for as variable consideration when estimating the amount of revenue to recognize. The estimate of variable consideration requires significant judgment. We have historically experienced a low rate of product returns and the total dollar value of product returns has not been significant to our financial statements. We recognize revenue when a performance obligation is satisfied by transferring the control of a product or providing service to a customer. Some of our contracts include the purchase of multiple products and/or services. In such cases, we allocate the transaction price based upon the relative estimated stand-alone price of each product and/or service sold. We record state and local sales taxes net; that is, we exclude sales tax from revenue. Typically, our contracts do not have a significant financing component. We incur incremental commission fees paid to the sales force associated with the sale of products. We apply the practical expedient within ASC 606-10-50-22 and have elected to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset the entity would otherwise recognize is one year or less. As a result, no commissions are capitalized as contract costs at June 30, 2018. The following is a description of the principal activities (separated by reportable segments) from which we generate our revenue. For more detailed information about our reportable segments including disaggregated revenue results by major product line and primary geographic markets, see “Note 16. Geographic and Segment Information”. Cardiac Surgery Products and Services The Cardiac Surgery (“CS”) segment has three primary product lines: cardiopulmonary products, heart valves and advanced circulatory support. Cardiopulmonary products include oxygenators, heart-lung machines, autotransfusion systems, perfusion tubing systems, cannulae and other related accessories. Heart valves include mechanical heart valves, tissue heart valves and related repair products. Technical services include installation, repair and maintenance of cardiopulmonary equipment under service contracts or upon customer request. Cardiopulmonary products may include performance obligations associated with assembly and installation of equipment. Accordingly, we allocate a portion of the sales prices to installation obligations and recognize that revenue when the service is provided. We recognize revenue for equipment and accessory product sales when control of the equipment or product passes to the customer. Heart valve revenue is recognized when control passes to the customer, usually at the point of surgery. Advanced circulatory support revenue, which represents our recently acquired TandemLife business, is principally derived from the sale of temporary life support product kits that can include a combination of pumps, oxygenators, and cannulae. Revenue is recognized when control passes to the customer, usually at the point of shipment. Technical service agreements generally provide for upfront payments in advance of rendering services or periodic billing over the contract term. Amounts billed in advance are deferred and recognized as revenue when the performance obligation is satisfied. Technical services are not a significant component of CS revenue and have been presented with the related equipment and accessories revenue. Neuromodulation Products Our Neuromodulation (“NM”) segment generates its revenue from the sale of neuromodulation therapy systems for the treatment of drug-resistant epilepsy, treatment-resistant depression and obstructive sleep apnea. The NM product line includes the VNS Therapy System, which consists of an implantable pulse generator, a lead that connects the generator to the vagus nerve, and other accessories. The NM product line also includes an implantable device for the treatment of obstructive sleep apnea that stimulates multiple tongue muscles via the hypoglossal nerve, which opens the airway while a patient is sleeping. We recognize revenue for product sales when control passes to the customer. Discontinued Operations: Cardiac Rhythm Management Products CRM generated revenue from the sale of products for the diagnosis, treatment, and management of heart rhythm disorders and heart failure. CRM devices include high-voltage defibrillators and low-voltage pacemakers. We recognize revenue for product sales when control passes to the customer. Contract Balances Due to the nature of our products and services, revenue producing activities may result in contract assets and contract liabilities which are insignificant to our financial position and results of operations. These activities relate primarily to CS technical services contracts for short-term and multi-year service agreements. Contract assets are primarily comprised of unbilled revenues, which occur when a performance obligation has been completed, but not billed to the customer. Contract liabilities are made up of deferred revenue, which occurs when a customer pays for a service, before a performance obligation has been completed. Contract assets are included within “Prepaid expenses and other current assets” in the condensed consolidated balance sheets and were insignificant at June 30, 2018 and December 31, 2017. As of June 30, 2018 and December 31, 2017, contract liabilities of $5.1 million and $3.8 million, respectively, are included within “Accrued liabilities and other” and “Other long-term liabilities” in the condensed consolidated balance sheets.

Note 2. Revenue Recognition

We generate our revenue through contracts with customers that primarily consist of hospitals, healthcare institutions, distributors and other organizations. Revenue is measured based on consideration specified in a contract with a customer, and excludes amounts collected on behalf of third parties. We measure the consideration based upon the estimated amount to be received. The amount of consideration we ultimately receive varies depending upon the return terms, sales rebates, discounts, and other incentives that we may offer, which are accounted for as variable consideration when estimating the amount of revenue to recognize. The estimate of variable consideration requires significant judgment.

We have historically experienced a low rate of product returns and the total dollar value of product returns has not been significant to our financial statements.

We recognize revenue when a performance obligation is satisfied by transferring the control of a product or providing service to a customer. Some of our contracts include the purchase of multiple products and/or services. In such cases, we allocate the transaction price based upon the relative estimated stand-alone price of each product and/or service sold. We record state and local sales taxes net; that is, we exclude sales tax from revenue. Typically, our contracts do not have a significant financing component.

We incur incremental commission fees paid to the sales force associated with the sale of products. We apply the practical expedient within ASC 606-10-50-22 and have elected to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset the entity would otherwise recognize is one year or less. As a result, no commissions are capitalized as contract costs at June 30, 2018.

The following is a description of the principal activities (separated by reportable segments) from which we generate our revenue. For more detailed information about our reportable segments including disaggregated revenue results by major product line and primary geographic markets, see “Note 16. Geographic and Segment Information”.

Cardiac Surgery Products and Services

The Cardiac Surgery (“CS”) segment has three primary product lines: cardiopulmonary products, heart valves and advanced circulatory support.

Cardiopulmonary products include oxygenators, heart-lung machines, autotransfusion systems, perfusion tubing systems, cannulae and other related accessories. Heart valves include mechanical heart valves, tissue heart valves and related repair products. Technical services include installation, repair and maintenance of cardiopulmonary equipment under service contracts or upon customer request.

Cardiopulmonary products may include performance obligations associated with assembly and installation of equipment. Accordingly, we allocate a portion of the sales prices to installation obligations and recognize that revenue when the service is provided. We recognize revenue for equipment and accessory product sales when control of the equipment or product passes to the customer.

Heart valve revenue is recognized when control passes to the customer, usually at the point of surgery.

Advanced circulatory support revenue, which represents our recently acquired TandemLife business, is principally derived from the sale of temporary life support product kits that can include a combination of pumps, oxygenators, and cannulae. Revenue is recognized when control passes to the customer, usually at the point of shipment.

Technical service agreements generally provide for upfront payments in advance of rendering services or periodic billing over the contract term. Amounts billed in advance are deferred and recognized as revenue when the performance obligation is satisfied. Technical services are not a significant component of CS revenue and have been presented with the related equipment and accessories revenue.

Neuromodulation Products

Our Neuromodulation (“NM”) segment generates its revenue from the sale of neuromodulation therapy systems for the treatment of drug-resistant epilepsy, treatment-resistant depression and obstructive sleep apnea. The NM product line includes the VNS Therapy System, which consists of an implantable pulse generator, a lead that connects the generator to the vagus nerve, and other accessories. The NM product line also includes an implantable device for the treatment of obstructive sleep apnea that stimulates multiple tongue muscles via the hypoglossal nerve, which opens the airway while a patient is sleeping. We recognize revenue for product sales when control passes to the customer.

Discontinued Operations: Cardiac Rhythm Management Products

CRM generated revenue from the sale of products for the diagnosis, treatment, and management of heart rhythm disorders and heart failure. CRM devices include high-voltage defibrillators and low-voltage pacemakers. We recognize revenue for product sales when control passes to the customer.

Contract Balances

Due to the nature of our products and services, revenue producing activities may result in contract assets and contract liabilities which are insignificant to our financial position and results of operations. These activities relate primarily to CS technical services contracts for short-term and multi-year service agreements. Contract assets are primarily comprised of unbilled revenues, which occur when a performance obligation has been completed, but not billed to the customer. Contract liabilities are made up of deferred revenue, which occurs when a customer pays for a service, before a performance obligation has been completed. Contract assets are included within “Prepaid expenses and other current assets” in the condensed consolidated balance sheets and were insignificant at June 30, 2018 and December 31, 2017. As of June 30, 2018 and December 31, 2017, contract liabilities of $5.1 million and $3.8 million, respectively, are included within “Accrued liabilities and other” and “Other long-term liabilities” in the condensed consolidated balance sheets.