Commitments and Contingencies	9 Months Ended
Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 13. Commitments and Contingencies From time to time, the Company is involved in legal and administrative proceedings and claims of various types. In some actions, the claimants seek damages, as well as other relief, which, if granted, would require significant expenditures. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in liability and the amount of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements. Thoratec Matters Thoratec Corporation (“Thoratec”), a subsidiary of Abbott Laboratories, has challenged a number of Company-owned patents in Europe in connection with the launch of Thoratec’s HeartMate PHPTM medical device (“PHP”) in Europe and the Company has counterclaimed for infringement in the District Court in Düsseldorf. The litigation was stayed pending the highest Court’s ruling on the validity and scope of the litigated patents. In September 2019, the Federal Court of Justice in Germany upheld the Company’s patents that are the subject of the patent infringement action for the sales and marketing of Thoratec’s PHP pump in Germany. Subsequently, the District Court in Düsseldorf lifted the stay and re-opened the litigation proceedings. These actions relate solely to Thoratec’s ability to manufacture and sell its PHP product in Europe and have no impact on the Company's ability to manufacture or sell its Impella® line of medical devices. The actions do not expose the Company to liability risk, except under local German law that requires a losing party in a proceeding to pay a portion of the other party’s legal fees. Maquet Matters In December 2015, the Company received a letter from Maquet Cardiovascular LLC (“Maquet”), a subsidiary of Getinge AB, asserting that the Company’s Impella^® devices infringe certain claims with guidewire, lumen, rotor, purge and sensor features, which were in two Maquet patents and one pending patent application (which has since issued as a third patent) in the U.S. and elsewhere, and attaching a draft litigation complaint. The letter encouraged the Company to take a license from Maquet. In May 2016, the Company filed suit in U.S. District Court for the District of Massachusetts (“D. Mass.” or “the Court”) against Maquet, seeking a declaratory judgment that the Company’s Impella devices do not infringe Maquet’s cited patent rights. The three Maquet patents will expire in September 2020, December 2020 and October 2021. In August 2016, Maquet sent a letter to the Company identifying four new Maquet U.S. continuation patent filings with claims that Maquet alleges are infringed by the Company’s Impella devices. The four U.S. continuation applications have been issued as patents of Maquet and will expire in September 2020. In September 2016, Maquet filed a response to the Company’s suit in D. Mass., including various counterclaims alleging that the Company’s Impella 2.5®, Impella CP®, Impella 5.0®, and Impella RP® heart pumps infringe certain claims of the three original issued U.S. patents (“2016 Action”). In July 2017, the Court granted a motion to add three of the four additional continuation patents to the 2016 Action. In April 2018, the Court conducted a Markman hearing on claim interpretation. On September 7, 2018, the judge issued a Memorandum and Order on Claim Construction, where he interpreted the disputed claim terms in the case. Maquet then filed a motion for reconsideration of the Court’s construction of one of the disputed claim terms. That motion was denied on May 22, 2019. The motion was denied on May 22, 2019. As a result of the Court’s denial, only one of the six originally asserted patents is in dispute. The Company filed a motion for summary judgement for the remaining patent on September 18, 2019. The parties briefed the motion on November 19, 2019 and are waiting for Court’s resolution. The Court has not set a date for trial. In November 2017, Maquet filed a second action in D. Mass (the “2017 Action”) alleging that the Company’s Impella 2.5^®, Impella CP^®, and Impella 5.0^® heart pumps infringe certain claims of the fourth additional U.S. continuation patent mentioned above (the seventh patent overall). Discovery in the 2017 Action is ongoing. In a series of letters during January and February 2019, Maquet informed the Company of seven new patent applications filed from the patents in the 2016 Action and 2017 Action with claims Maquet alleges would be infringed by the Impella® products if the new applications were to issue as patents. All seven applications issued as patents between February and July of 2019 and will expire in September 2020. One of the newly issued patents has been added to the 2017 Action. A Markman hearing for the newly-added patent was held on November 18, 2019. A Markman order has not been issued yet. Discovery remains ongoing. In the 2016 Action and 2017 Action, Maquet seeks injunctive relief and monetary damages in the form of a reasonable royalty, with three times the amount for alleged willful infringement. In its responses to the Company’s counterclaims, Maquet admits that its current commercially available products do not embody the claims of the asserted patents. The Company is unable to estimate the potential liability with respect to the legal matters noted above. There are numerous factors that make it difficult to meaningfully estimate possible loss or range of loss at this stage of the legal proceedings, including the significant number of legal and factual issues still to be resolved in the Maquet and Thoratec patent disputes. Securities Class Action Litigation On or about August 6, 2019, the Company received a securities class action complaint filed on behalf of a single shareholder in the U.S. District Court for the Southern District of New York (“SDNY”), on behalf of himself and persons or entities that purchased or acquired the Company’s securities between January 31, 2019 through July 31, 2019. On October 7, 2019, a similar purported class action complaint was filed by a different shareholder on behalf of himself and persons or entities that purchased or acquired the Company’s securities between November 1, 2018 and July 31, 2019. Also, on October 7, 2019, four shareholders filed applications to be appointed lead plaintiff and for their counsel to be appointed lead counsel for the class. Two of those shareholders also filed motions to consolidate the two cases. Since October 7, 2019, two of the shareholders have withdrawn their applications to be lead plaintiff. After the court selects one of the two remaining shareholders as lead plaintiff, that plaintiff is expected to file an amended complaint. The complaints allege that the Company violated Sections 10(b) and 20(a) of and Rule 10b-5 under the Exchange Act, in connection with allegedly misleading disclosures made by the Company regarding its financial condition and results of operations. The Company has reviewed and not yet responded to the complaints. The Company believes that the allegations are without merit and plans to defend itself vigorously. Shareholder Derivative Litigation On November 6 and 7, 2019, two shareholders filed derivative actions in SDNY that were subsequently consolidated. On November 8, 2019, another shareholder filed a derivative action in Massachusetts Suffolk County Superior Court. On January 7, 2020, another shareholder derivative action was filed in the U.S. District Court for the District of Delaware. The complaints in these actions rely on many of the same allegations as in the securities class actions, and assert that, between November 1, 2018 and July 31, 2019, the directors of the Company made or allowed to be made misleading public statements regarding the Company’s growth, ultimately harming the Company. The Company has agreed with plaintiffs in the consolidated SDNY and Delaware actions to stay those cases pending resolution of a motion to dismiss in the securities class actions, and is negotiating a similar stay with the plaintiff in the Massachusetts case. On January 27, 2020, the Delaware case was administratively closed and subject to reopening after resolution of a motion to dismiss in the securities class actions. The Company is unable to estimate the potential liability with respect to the legal matters noted above. There are numerous factors that make it difficult to estimate reasonably possible loss or range of loss at this stage of the legal proceedings, including the significant number of legal and factual issues still to be resolved in the securities class action litigation.

Commitments and Contingencies

9 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Note 13. Commitments and Contingencies

From time to time, the Company is involved in legal and administrative proceedings and claims of various types. In some actions, the claimants seek damages, as well as other relief, which, if granted, would require significant expenditures. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in liability and the amount of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements.

Thoratec Matters

Thoratec Corporation (“Thoratec”), a subsidiary of Abbott Laboratories, has challenged a number of Company-owned patents in Europe in connection with the launch of Thoratec’s HeartMate PHPTM medical device (“PHP”) in Europe and the Company has counterclaimed for infringement in the District Court in Düsseldorf. The litigation was stayed pending the highest Court’s ruling on the validity and scope of the litigated patents. In September 2019, the Federal Court of Justice in Germany upheld the Company’s patents that are the subject of the patent infringement action for the sales and marketing of Thoratec’s PHP pump in Germany. Subsequently, the District Court in Düsseldorf lifted the stay and re-opened the litigation proceedings.

These actions relate solely to Thoratec’s ability to manufacture and sell its PHP product in Europe and have no impact on the Company's ability to manufacture or sell its Impella® line of medical devices. The actions do not expose the Company to liability risk, except under local German law that requires a losing party in a proceeding to pay a portion of the other party’s legal fees.

Maquet Matters

In December 2015, the Company received a letter from Maquet Cardiovascular LLC (“Maquet”), a subsidiary of Getinge AB, asserting that the Company’s Impella^® devices infringe certain claims with guidewire, lumen, rotor, purge and sensor features, which were in two Maquet patents and one pending patent application (which has since issued as a third patent) in the U.S. and elsewhere, and attaching a draft litigation complaint. The letter encouraged the Company to take a license from Maquet. In May 2016, the Company filed suit in U.S. District Court for the District of Massachusetts (“D. Mass.” or “the Court”) against Maquet, seeking a declaratory judgment that the Company’s Impella devices do not infringe Maquet’s cited patent rights. The three Maquet patents will expire in September 2020, December 2020 and October 2021.

In August 2016, Maquet sent a letter to the Company identifying four new Maquet U.S. continuation patent filings with claims that Maquet alleges are infringed by the Company’s Impella devices. The four U.S. continuation applications have been issued as patents of Maquet and will expire in September 2020.

In September 2016, Maquet filed a response to the Company’s suit in D. Mass., including various counterclaims alleging that the Company’s Impella 2.5®, Impella CP®, Impella 5.0®, and Impella RP® heart pumps infringe certain claims of the three original issued U.S. patents (“2016 Action”). In July 2017, the Court granted a motion to add three of the four additional continuation patents to the 2016 Action. In April 2018, the Court conducted a Markman hearing on claim interpretation. On September 7, 2018, the judge issued a Memorandum and Order on Claim Construction, where he interpreted the disputed claim terms in the case. Maquet then filed a motion for reconsideration of the Court’s construction of one of the disputed claim terms. That motion was denied on May 22, 2019. The motion was denied on May 22, 2019. As a result of the Court’s denial, only one of the six originally asserted patents is in dispute. The Company filed a motion for summary judgement for the remaining patent on September 18, 2019. The parties briefed the motion on November 19, 2019 and are waiting for Court’s resolution. The Court has not set a date for trial.

In November 2017, Maquet filed a second action in D. Mass (the “2017 Action”) alleging that the Company’s Impella 2.5^®, Impella CP^®, and Impella 5.0^® heart pumps infringe certain claims of the fourth additional U.S. continuation patent mentioned above (the seventh patent overall). Discovery in the 2017 Action is ongoing.

In a series of letters during January and February 2019, Maquet informed the Company of seven new patent applications filed from the patents in the 2016 Action and 2017 Action with claims Maquet alleges would be infringed by the Impella® products if the new applications were to issue as patents. All seven applications issued as patents between February and July of 2019 and will expire in September 2020. One of the newly issued patents has been added to the 2017 Action. A Markman hearing for the newly-added patent was held on November 18, 2019. A Markman order has not been issued yet. Discovery remains ongoing.

In the 2016 Action and 2017 Action, Maquet seeks injunctive relief and monetary damages in the form of a reasonable royalty, with three times the amount for alleged willful infringement. In its responses to the Company’s counterclaims, Maquet admits that its current commercially available products do not embody the claims of the asserted patents.

The Company is unable to estimate the potential liability with respect to the legal matters noted above. There are numerous factors that make it difficult to meaningfully estimate possible loss or range of loss at this stage of the legal proceedings, including the significant number of legal and factual issues still to be resolved in the Maquet and Thoratec patent disputes.

Securities Class Action Litigation

On or about August 6, 2019, the Company received a securities class action complaint filed on behalf of a single shareholder in the U.S. District Court for the Southern District of New York (“SDNY”), on behalf of himself and persons or entities that purchased or acquired the Company’s securities between January 31, 2019 through July 31, 2019. On October 7, 2019, a similar purported class action complaint was filed by a different shareholder on behalf of himself and persons or entities that purchased or acquired the Company’s securities between November 1, 2018 and July 31, 2019. Also, on October 7, 2019, four shareholders filed applications to be appointed lead plaintiff and for their counsel to be appointed lead counsel for the class. Two of those shareholders also filed motions to consolidate the two cases. Since October 7, 2019, two of the shareholders have withdrawn their applications to be lead plaintiff. After the court selects one of the two remaining shareholders as lead plaintiff, that plaintiff is expected to file an amended complaint.

The complaints allege that the Company violated Sections 10(b) and 20(a) of and Rule 10b-5 under the Exchange Act, in connection with allegedly misleading disclosures made by the Company regarding its financial condition and results of operations. The Company has reviewed and not yet responded to the complaints. The Company believes that the allegations are without merit and plans to defend itself vigorously.

Shareholder Derivative Litigation

On November 6 and 7, 2019, two shareholders filed derivative actions in SDNY that were subsequently consolidated. On November 8, 2019, another shareholder filed a derivative action in Massachusetts Suffolk County Superior Court. On January 7, 2020, another shareholder derivative action was filed in the U.S. District Court for the District of Delaware. The complaints in these actions rely on many of the same allegations as in the securities class actions, and assert that, between November 1, 2018 and July 31, 2019, the directors of the Company made or allowed to be made misleading public statements regarding the Company’s growth, ultimately harming the Company.

The Company has agreed with plaintiffs in the consolidated SDNY and Delaware actions to stay those cases pending resolution of a motion to dismiss in the securities class actions, and is negotiating a similar stay with the plaintiff in the Massachusetts case. On January 27, 2020, the Delaware case was administratively closed and subject to reopening after resolution of a motion to dismiss in the securities class actions.

The Company is unable to estimate the potential liability with respect to the legal matters noted above. There are numerous factors that make it difficult to estimate reasonably possible loss or range of loss at this stage of the legal proceedings, including the significant number of legal and factual issues still to be resolved in the securities class action litigation.