Abiomed (ABMD) 10-Q 6 Nov 18 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Sep. 30, 2018	Oct. 25, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,019
Document Fiscal Period Focus	Q2
Trading Symbol	ABMD
Entity Registrant Name	ABIOMED INC
Entity Central Index Key	815,094
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		45,039,527

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents	$ 76,382	$ 42,975
Short-term marketable securities	334,064	319,274
Accounts receivable, net	74,201	70,010
Inventories	63,656	50,204
Prepaid expenses and other current assets	13,296	11,808
Total current assets	561,599	494,271
Long-term marketable securities		37,502
Property and equipment, net	134,065	117,167
Goodwill	33,719	35,808
In-process research and development	15,730	16,705
Long-term deferred tax assets, net	116,248	70,746
Other assets	25,804	14,176
Total assets	887,165	786,375
Current liabilities:
Accounts payable	21,884	23,565
Accrued expenses	46,099	46,147
Deferred revenue	13,996	14,970
Total current liabilities	81,979	84,682
Other long-term liabilities	889	776
Contingent consideration	10,493	10,490
Long-term deferred tax liabilities	850	903
Total liabilities	94,211	96,851
Commitments and contingencies (Note 11)
Stockholders' equity:
Class B Preferred Stock, $.01 par value Authorized - 1,000,000 shares; Issued and outstanding - none
Common stock, $.01 par value Authorized - 100,000,000 shares; Issued - 46,935,424 shares at September 30, 2018 and 46,100,649 shares at March 31, 2018 Outstanding - 45,038,453 shares at September 30, 2018 and 44,375,337 shares at March 31, 2018	450	444
Additional paid in capital	660,132	619,905
Retained earnings	280,650	140,457
Treasury stock at cost - 1,896,971 shares at September 30, 2018 and 1,725,312 shares at March 31, 2018	(136,743)	(67,078)
Accumulated other comprehensive loss	(11,535)	(4,204)
Total stockholders' equity	792,954	689,524
Total liabilities and stockholders' equity	$ 887,165	$ 786,375

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2018	Mar. 31, 2018
Statement Of Financial Position [Abstract]
Class B Preferred Stock, par value	$ 0.01	$ 0.01
Class B Preferred Stock, Authorized	1,000,000	1,000,000
Class B Preferred Stock, Issued	0	0
Class B Preferred Stock, outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, Authorized	100,000,000	100,000,000
Common stock, Issued	46,935,424	46,100,649
Common stock, Outstanding	45,038,453	44,375,337
Treasury stock, shares	1,896,971	1,725,312

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 181,778	$ 132,823	$ 361,788	$ 265,291
Costs and expenses:
Cost of revenue	29,846	21,627	60,696	43,489
Research and development	22,717	19,390	43,990	36,321
Selling, general and administrative	78,895	60,080	160,034	120,677
Costs and Expenses, Total	131,458	101,097	264,720	200,487
Income from operations	50,320	31,726	97,068	64,804
Other income:
Investment income, net	1,671	781	3,222	1,416
Other (expense) income, net	(158)	(23)	30	56
Nonoperating Income (Expense), Total	1,513	758	3,252	1,472
Income before income taxes	51,833	32,484	100,320	66,276
Income tax provision (benefit)	1,706	7,981	(39,873)	4,399
Net income	$ 50,127	$ 24,503	$ 140,193	$ 61,877
Basic net income per share	$ 1.11	$ 0.56	$ 3.13	$ 1.41
Basic weighted average shares outstanding	44,961	44,141	44,754	44,018
Diluted net income per share	$ 1.09	$ 0.54	$ 3.04	$ 1.36
Diluted weighted average shares outstanding	46,153	45,698	46,164	45,655

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 50,127	$ 24,503	$ 140,193	$ 61,877
Other comprehensive (loss) gain:
Foreign currency translation (losses) gains	(600)	2,696	(7,452)	8,849
Net unrealized (losses) gains on marketable securities	(22)	10	121	(45)
Other comprehensive (loss) gain	(622)	2,706	(7,331)	8,804
Comprehensive income	$ 49,505	$ 27,209	$ 132,862	$ 70,681

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net income	$ 140,193	$ 61,877
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation expense	6,347	5,320
Bad debt expense (recovery)	467	(54)
Stock-based compensation	28,179	17,938
Write-down of inventory and other	1,733	2,528
Accretion on marketable securities	(848)
Deferred tax provision	(45,676)	3,073
Change in fair value of contingent consideration	3	682
Changes in assets and liabilities:
Accounts receivable	(5,131)	(2,824)
Inventories	(16,750)	(5,363)
Prepaid expenses and other assets	(1,987)	(869)
Accounts payable	761	299
Accrued expenses and other liabilities	826	(3,174)
Deferred revenue	(926)	18
Net cash provided by operating activities	107,191	79,451
Investing activities:
Purchases of marketable securities	(112,956)	(131,934)
Proceeds from the sale and maturity of marketable securities	136,844	95,416
Purchase of other assets	(11,426)	(6,400)
Purchases of property and equipment	(27,345)	(17,675)
Net cash used for investing activities	(14,883)	(60,593)
Financing activities:
Proceeds from the exercise of stock options	10,613	5,257
Taxes paid related to net share settlement of vesting of stock awards	(69,666)	(19,237)
Proceeds from the issuance of stock under employee stock purchase plan	1,375	1,063
Principal payments on capital lease obligation		(377)
Net cash used for financing activities	(57,678)	(13,294)
Effect of exchange rate changes on cash	(1,223)	(68)
Net increase in cash and cash equivalents	33,407	5,496
Cash and cash equivalents at beginning of period	42,975	39,040
Cash and cash equivalents at end of period	76,382	44,536
Supplemental disclosure of cash flow information:
Cash paid for income taxes	3,530	584
Cash paid for interest on capital lease obligation		259
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment in accounts payable and accrued expenses	$ 1,399	$ 897

Nature of Business

Nature of Business	6 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Nature of Business	Note 1. Nature of Business ABIOMED, Inc. (the “Company” or “Abiomed”) is a provider of mechanical circulatory support devices and offers a continuum of care to heart failure patients. The Company develops, manufactures and markets proprietary products that are designed to enable the heart to rest, heal and recover by improving blood flow and/or performing the pumping function of the heart. The Company’s products are used in the cardiac catheterization lab, or cath lab, by interventional cardiologists and in the heart surgery suite by cardiac surgeons for patients who are in need of hemodynamic support prophylactically or emergently before, during or after angioplasty or heart surgery procedures.

Basis of Preparation and Summar

Basis of Preparation and Summary of Significant Accounting Policies	6 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Preparation and Summary of Significant Accounting Policies	Note 2. Basis of Preparation and Summary of Significant Accounting Policies The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial reporting and in accordance with Article 10 of Regulation S-X. Accordingly, they do not include all of the information and note disclosures required by GAAP for complete financial statements. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2018 that has been filed with the Securities and Exchange Commission (“SEC”). In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all normal and recurring adjustments that are necessary for a fair presentation of results for the interim periods presented. The results of operations for any interim period may not be indicative of results for the full fiscal year or any other subsequent period. There have been no changes in the Company’s significant accounting policies for the three and six months ended September 30, 2018 as compared to the significant accounting policies described in the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2018 that has been filed with the SEC. New Accounting Pronouncements Adopted Effective April 1, 2018, the Company adopted the Financial Accounting Standards Board (“FASB”) standard update ASU 2014-09, “Revenue from Contracts with Customers,” (“Topic 606”) which provides a principles-based, five-step approach to measure and recognize revenue from contracts with customers. The adoption of this guidance did not have a material impact on the Company’s consolidated statement of operations, cash flows, and balance sheet as of the adoption date or for the three or six months ended September 30, 2018. Additional information and disclosures required by this new standard are contained in “Note 4. Revenue Recognition,” to the Company’s consolidated financial statements. Effective April 1, 2018, the Company adopted the FASB standard update ASU 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities,” which requires certain financial assets to be measured at fair value with changes in fair value recognized in the statement of operations. The adoption of this guidance did not have a material impact on the Company’s consolidated statement of operations, cash flows, and balance sheet as of the adoption date or for the three or six months ended September 30, 2018. Additional information and disclosures required by this new standard are contained in “Note 5. Cash Equivalents, Marketable Securities, and Fair Value Measurements,” to the Company’s consolidated financial statements. On June 20, 2018, the FASB issued ASU 2018-07, “Compensation – Stock Compensation (“Topic 718”): Improvements to Nonemployee Share-Based Payment Accounting,” which simplifies the accounting for share-based payments granted to nonemployees for goods and services. ASU 2018-07 eliminated the previous guidance for accounting for share-based payments to nonemployees and expanded Topic 718 to include share-based payments transactions to nonemployees. ASU 2018-07 is effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted, but no earlier than an entity’s adoption date of Topic 606. The adoption of ASU 2018-07 requires a modified retrospective transition approach, with a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year. The Company early adopted ASU 2018-07 on June 20, 2018. The adoption of this guidance did not have a material impact on the Company’s consolidated statements of operations, cash flows, and balance sheet as of the adoption date or for the three or six months ended September 30, 2018. Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, “Leases.” The new guidance significantly impacts lessee accounting and financial statement disclosures. Specifically, this guidance requires lessees to identify arrangements that should be accounted for as leases. Under this guidance, for lease arrangements exceeding a one year term, a right-of-use asset and lease obligation is recorded by the lessee for all leases on the balance sheet, whether operating or financing, while the statement of operations includes lease expense for operating leases and amortization and interest expense for financing leases. The lease obligation amount recorded on the balance sheet at the date of adoption of this guidance must be calculated using the applicable incremental borrowing rate at the date of adoption. Leases with a term of one year or less will be accounted for similar to existing guidance for operating leases. The Company is currently in the process of evaluating its lease arrangements to determine the impact of ASU 2016-02 on its consolidated financial statements as well as updating processes and controls in order to adopt the new standard. This evaluation includes a review of the Company’s existing leasing arrangements on its facilities. In addition, the evaluation includes a review of the Company’s existing contracts with its suppliers and vendors to determine if these agreements contain an embedded lease. The Company currently expects that its lease commitments will be recognized as operating lease liabilities and right-of-use assets upon adoption, which will increase total assets and total liabilities that the Company reports on its consolidated balance sheet. ASU 2016-02 must be adopted using a modified retrospective approach for all leases existing at, or entered into after the date of initial adoption, with an option to elect to use certain transition relief. ASU 2016-02 will become effective for the Company on April 1, 2019.

Net Income Per Share

Net Income Per Share	6 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Net Income Per Share	Note 3. Net Income Per Share Basic net income per share is computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted net income per share is computed by dividing net income by the weighted average number of dilutive common shares outstanding during the period. Diluted shares outstanding are calculated by adding to the weighted average shares outstanding any potential dilutive securities outstanding for the period. Potential dilutive securities include stock options, restricted stock units, performance-based stock awards and shares to be purchased under the Company’s employee stock purchase plan. The Company’s basic and diluted net income per share for the three and six months ended September 30, 2018 and 2017 were as follows (in thousands, except per share data): For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Basic Net Income Per Share Net income $ 50,127 $ 24,503 $ 140,193 $ 61,877 Basic weighted average shares outstanding 44,961 44,141 44,754 44,018 Basic net income per share $ 1.11 $ 0.56 $ 3.13 $ 1.41 For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Diluted Net Income Per Share Net income $ 50,127 $ 24,503 $ 140,193 $ 61,877 Basic weighted average shares outstanding 44,961 44,141 44,754 44,018 Effect of dilutive securities 1,192 1,557 1,410 1,637 Diluted weighted average shares outstanding 46,153 45,698 46,164 45,655 Diluted net income per share $ 1.09 $ 0.54 $ 3.04 $ 1.36 For the three and six months ended September 30, 2018, approximately 4,000 and 54,000 shares underlying out-of-the-money stock options, respectively, were excluded in the computation of diluted earnings per share because their effect would have been anti-dilutive. Also, approximately 97,000 restricted shares in each of the three and six months ended September 30, 2018, respectively, related to performance-based awards for which milestones have not been met, were not included in the computation of diluted earnings per share. For the three and six months ended September 30, 2017, approximately 200 and 5,700 77,000

Revenue Recognition

Revenue Recognition	6 Months Ended
	Sep. 30, 2018
Revenue Recognition And Deferred Revenue [Abstract]
Revenue Recognition	Note 4. Revenue Recognition Adoption of Topic 606, Revenue from Contracts with Customers The Company adopted Topic 606 on April 1, 2018, using the modified retrospective method for all contracts not completed as of the date of adoption. The reported results for fiscal year 2019 reflect the application of Topic 606 guidance while the reported results for fiscal year 2018 were prepared under the guidance of ASC 605, “Revenue Recognition.” The adoption of Topic 606 did not have a material impact on the timing or amount of revenue recognized upon adoption and there was no cumulative prior period adjustment recorded to the opening balance of retained earnings upon adoption. Accordingly, the adoption of Topic 606 did not have a material impact on the Company’s consolidated balance sheet, statement of operations, stockholders’ equity or cash flows as of the adoption date or for the three or six months ended September 30, 2018. The Company has made the following accounting policy elections and elected to use certain practical expedients, as permitted by the FASB, in applying Topic 606: (1) the Company accounts for amounts collected from customers for sales and other taxes, net of related amounts remitted to tax authorities; (2) the Company does not adjust the promised amount of consideration for the effects of a significant financing component because, at contract inception, the Company expects the period between the time when the Company transfers a promised good or service to the customer and the time when the customer pays for that good or service will be one year or less; (3) the Company expenses costs to obtain a contract as they are incurred if the expected period of benefit, and therefore the amortization period, is one year or less; (4) the Company accounts for shipping and handling activities that occur after control transfers to the customer as a fulfillment cost rather than an additional promised service and these fulfillment costs are recorded as selling, general and administrative expenses; (5) the Company does not assess whether promised goods or services are performance obligations if they are immaterial in the context of the contract with the customer; and (6) the Company does not disclose the transaction price allocated to unsatisfied performance obligations when the original expected contract duration is one year or less. The Company generates revenue primarily from the sale of Impella 2.5, Impella CP, Impella 5.0, Impella LD, Impella RP and Impella AIC products. The Company also generates revenue from preventative maintenance service contracts and maintenance calls. The Company determines revenue recognition through the following steps: • Identification of the contract, or contracts, with a customer • Identification of the performance obligation in the contract • Determination of the transaction price • Allocation of the transaction price to the performance obligation in the contract • Recognition of revenue when, or as, a performance obligation is satisfied Contracts and Performance Obligations The Company accounts for a contract with a customer when there is an approval and commitment from both parties, the rights of the parties are identified, payment terms are identified, the contract has commercial substance and collectability of the consideration is probable. The Company's performance obligations consist mainly of transferring control of products and services identified in the contracts, purchase orders or invoices. For each contract, the Company considers the obligation to transfer products and services to the customer, each of which are distinct, to be performance obligations. Transaction price and allocation to performance obligations Transaction prices of products or services are typically based on contracted rates. To the extent that the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing the expected value method or the most likely amount, depending on the circumstances, to which the Company expects to be entitled. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on an assessment of the Company’s anticipated performance and all information (historical, current and forecasted) that is reasonably available. Sales and other taxes collected on behalf of third parties are excluded from revenue. The Company does not provide for rights of return to customers on product sales and, therefore, does not record a provision for returns. Customers typically have a limited time frame to notify the Company of any defective or non-conforming products. The Company’s limited warranty provision is accounted for using the cost accrual method and is recognized as expense when products are sold and is not considered a separate performance obligation. If a contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price based on the estimated relative standalone selling prices of the promised products or services underlying each performance obligation. The Company determines standalone selling prices based on the price at which the performance obligation is sold separately. Revenue Recognition Revenue is recognized when, or as, obligations under the terms of a contract are satisfied, which occurs when control of the promised products or services is transferred to customers. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring products or services to a customer. Product revenue is generally recognized when the customer obtains control of the Company’s product, which occurs at a point in time, and may be upon shipment or upon delivery based on the contractual shipping terms of a contract. Service revenue is generally recognized over time as the services are rendered to the customer based on the extent of progress towards completion of the performance obligation. The Company recognizes service revenue over the term of the service contract. Services are expected to be transferred to the customer throughout the term of the contract and the Company believes recognizing revenue ratably over the term of the contract best depicts the transfer of value to the customer. Revenue generated from preventative maintenance calls is recognized at a point in time when the services are provided to the customer. Revenue from the sale of products and services are evidenced by either a contract with the customer or a valid purchase order and an invoice which includes all relevant terms of sale. The Company performs a review of each specific customer's credit worthiness and ability to pay prior to acceptance as a customer. Further, the Company performs periodic reviews of its customers' creditworthiness prospectively. Disaggregation of Revenue The Company generally sells its Impella products and services through a direct sales force in the U.S. and Germany and through direct sales and distribution agreements in other international markets outside (e.g. in: Europe, Canada, Latin America, Asia-Pacific). Revenue is disaggregated from contracts between product revenue and service and other revenue and by geography, which the Company believes best depicts how the nature, amount, timing, and uncertainty of revenues and cash flows are affected by economic factors. The following table disaggregates the Company’s revenue by products and services: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) Impella product revenue $ 175,270 $ 127,400 $ 348,945 $ 254,594 Service and other revenue 6,508 5,423 12,843 10,697 Total revenue $ 181,778 $ 132,823 $ 361,788 $ 265,291 The following table disaggregates the Company’s revenue by geographical location: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) U.S. revenue $ 158,243 $ 118,669 $ 315,838 $ 238,335 International revenue 23,535 14,154 45,950 26,956 Total revenue $ 181,778 $ 132,823 $ 361,788 $ 265,291 Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established and which result from discounts or rebates that are offered within contracts between the Company and its customers relating to the Company’s sales of its products. These reserves are based on the amounts earned or are expected to be claimed on the related sales and are classified as reductions of accounts receivable. Where appropriate, these estimates take into consideration relevant factors such as the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. These reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company adjusts these estimates, which would affect net product revenue and earnings in the period such variances become known. Rebates and Discounts The Company provides certain customers with rebates and discounts that are defined in the Company’s contract arrangements with customers and are recorded as a reduction of revenue in the period the related product revenue is recognized, resulting in a reduction to revenue and the establishment of a liability, which are all included in accrued expenses in the accompanying consolidated balance sheets. Rebates normally result from performance-based offers that are primarily based on attaining contractually specified sales volumes as well as product usage. Discounts are normally from early payment incentives. The Company estimates the amount of rebates and discounts based on an estimate of the third party’s sales and the respective rebate or discount defined in the customer contractual arrangement. The following table summarizes product revenue rebates and discounts for the six months ended September 30, 2018 (in thousands): Rebates and Discounts Balance at March 31, 2018 $ 1,405 Provision related to current period revenue 989 Credits and adjustments made during the period (869 ) Balance at September 30, 2018 $ 1,525 Contract Balances The timing of revenue recognition, billings and cash collections results in trade receivables and deferred revenue on the consolidated balance sheet. A receivable is recognized in the period the Company’s right to the consideration from the customer is unconditional. The change in the accounts receivable balances relate to the timing of revenue recognition, billings and cash collections. The Company generally does not have any performance obligations with a term of more than one year. Payment terms vary by contract type and type of customer and generally range from 30 to 60 days for direct sales customers. Payment terms with certain international distributors can be up to 90 days. The Company’s contracts with customers do not typically include extended payment terms. Deferred Revenue When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, deferred revenue is recorded. Deferred revenue is recognized as revenue after control of the products or services is transferred to the customer and all revenue recognition criteria have been met. The Company’s deferred revenue balance was $14.0 million as of September 30, 2018 and $15.0 million as of March 31, 2018. The change relates to the timing of product shipment and completion of recognizing revenue when the customer obtains control of the product and additional preventative maintenance service contracts and the subsequent recognition of the contract ratably over the term of the service contract. During the three and six months ended September 30, 2018, the Company recognized $3.3 million and $12.4 million of revenue that was included in the deferred revenue balance as of March 31, 2018, respectively. Costs to Obtain or Fulfill a Customer Contract The Company has certain costs to obtain and fulfill a customer contract, such as commissions and shipping costs. The Company recognizes the incremental costs of obtaining contracts as an expense when incurred if the amortization period of the assets that the Company otherwise would have recognized is one year or less. The Company accounts for shipping and handling activities related to contracts with customers as costs to fulfill the promise to transfer the associated products. These costs are included in selling, general, and administrative expenses.

Cash Equivalents Marketable Sec

Cash Equivalents Marketable Securities and Fair Value Measurements	6 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Cash Equivalents, Marketable Securities and Fair Value Measurements	Note 5. Cash Equivalents, Marketable Securities and Fair Value Measurements The Company classifies any marketable security with a maturity date of 90 days or less at the time of purchase as a cash equivalent. Cash equivalents are carried on the balance sheet at fair market value. The Company’s marketable securities, consisting of U.S. Treasuries, U.S. Government Agency, corporate debt securities, and commercial paper, are classified as available-for-sale securities and, accordingly, are recorded at fair value. The difference between amortized cost and fair value is included in stockholders’ equity. At September 30, 2018 and March 31, 2018, the Company’s financial instruments consisted primarily of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and contingent consideration. The carrying amounts of accounts receivable and accounts payable are considered reasonable estimates of their fair value, due to the short maturity of these investments. The Company’s cash equivalents and marketable securities at September 30, 2018 and March 31, 2018 are classified on the balance sheet as follows: September 30, 2018 March 31, 2018 (in $000's) Cash equivalents $ 17,768 $ 22,595 Short-term marketable securities 334,064 319,274 Long-term marketable securities — 37,502 $ 351,832 $ 379,371 The Company’s cash equivalents and marketable securities at September 30, 2018 and March 31, 2018 are invested in the following: Amortized Gross Unrealized Gross Unrealized Fair Market Cost Gains Losses Value (in $000's) September 30, 2018: Money market funds $ 17,768 $ — $ — $ 17,768 Short-term U.S. Treasury mutual fund securities 39,729 — (63 ) 39,666 Short-term government-backed securities 204,018 — (349 ) 203,669 Short-term corporate debt securities 54,477 — (54 ) 54,423 Short-term commercial paper 36,326 — (20 ) 36,306 $ 352,318 $ — $ (486 ) $ 351,832 Amortized Gross Unrealized Gross Unrealized Fair Market Cost Gains Losses Value (in $000's) March 31, 2018: Money market funds $ 5,845 $ — $ — $ 5,845 Repurchase agreements 16,750 — — 16,750 Short-term U.S. Treasury mutual fund securities 18,132 — (29 ) 18,103 Short-term government-backed securities 212,255 3 (538 ) 211,720 Short-term corporate debt securities 52,737 — (161 ) 52,576 Short-term commercial paper 36,936 2 (63 ) 36,875 Long-term U.S. Treasury mutual fund securities 10,953 — (16 ) 10,937 Long-term government-backed securities 24,798 1 (12 ) 24,787 Long-term corporate debt securities 1,777 1 — 1,778 $ 380,183 $ 7 $ (819 ) $ 379,371 Fair Value Hierarchy Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three categories: Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that are not corroborated by market data. Level 1 primarily consists of financial instruments whose values are based on quoted market prices such as exchange-traded instruments and listed equities. Level 2 includes financial instruments that are valued using models or other valuation methodologies. These models are primarily industry-standard models that consider various assumptions, including time value, yield curve, volatility factors, prepayment speeds, default rates, loss severity, current market and contractual prices for the underlying financial instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace. Level 3 is comprised of unobservable inputs that are supported by little or no market activity. Financial assets are considered Level 3 when their fair values are determined using pricing models, discounted cash flows, or similar techniques, and at least one significant model assumption or input is unobservable. The following table presents the Company’s financial instruments recorded at fair value in the consolidated balance sheets, classified according to the three categories described above: Level 1 Level 2 Level 3 Total September 30, 2018: (in $000's) Assets Money market funds $ 17,768 $ — $ — $ 17,768 Short-term U.S. Treasury mutual fund securities — 39,666 — 39,666 Short-term government-backed securities — 203,669 — 203,669 Short-term corporate debt securities — 54,423 — 54,423 Short-term commercial paper — 36,306 — 36,306 Liabilities Contingent consideration — — 10,493 10,493 Level 1 Level 2 Level 3 Total March 31, 2018: (in $000's) Assets Money market funds $ 5,845 $ — $ — $ 5,845 Repurchase agreements — 16,750 — 16,750 Short-term U.S. Treasury mutual fund securities — 18,103 — 18,103 Short-term government-backed securities — 211,720 — 211,720 Short-term corporate debt securities — 52,576 — 52,576 Short-term commercial paper — 36,875 — 36,875 Long-term U.S. Treasury mutual fund securities — 10,937 — 10,937 Long-term government-backed securities — 24,787 — 24,787 Long-term corporate debt securities — 1,778 — 1,778 Liabilities Contingent consideration — — 10,490 10,490 The Company has determined that the estimated fair value of its money market funds are reported as Level 1 financial assets as they are valued at quoted market prices in active markets. The Company has determined that the estimated fair value of its investments in U.S. Treasury mutual fund securities, government-backed securities, corporate debt securities, repurchase agreements and commercial paper are reported as Level 2 financial assets as they are not exchange-traded instruments. The Company’s financial liabilities consisted of contingent consideration potentially payable related to the acquisition of ECP Entwicklungsgesellschaft mbH, (“ECP”) and AIS GmbH Aachen Innovative Solutions, (“AIS’), in July 2014. The Company acquired ECP for $13.0 million in cash, with additional potential payouts totaling $15.0 million based on the achievement of CE Mark approval in the European Union and a revenue-based milestone related to the development of the future Impella ECP TM robabilities were applied to each potential scenario and the resulting values were discounted using a rate that considers weighted average cost of capital as well as a specific risk premium associated with the riskiness of the earn out itself, the related projections, and the overall business. The r This liability is reported as Level 3 as the estimated fair value of the contingent consideration related to the acquisition of ECP requires significant management judgment or estimation and is calculated using the following valuation methods: Milestone Payment Fair Value at September 30, 2018 (in $000's) Valuation Methodology Significant Unobservable Input Weighted Average (range, if applicable) Clinical and regulatory milestone $ 7,000 $ 5,767 Probability weighted income approach Projected fiscal year of milestone payments 2019 to 2022 Discount rate 3.9% to 4.2% Probability of occurrence Probability adjusted level of 40% for the base case scenario and 10% to 40% for various upside and downside scenarios Revenue-based milestone 8,000 4,726 Monte Carlo simulation model Projected fiscal year of milestone payments 2024 to 2035 Discount rate 15% Expected volatility for forecasted revenues 50% Probability of payment 79% $ 15,000 $ 10,493 The following table summarizes the change in fair value, as determined by Level 3 inputs, of the contingent consideration for the three and six months ended September 30, 2018 and 2017: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) Level 3 liabilities, beginning balance $ 10,331 $ 9,418 $ 10,490 $ 9,153 Additions — — — — Payments — — — — Change in fair value 162 417 3 682 Level 3 liabilities, ending balance $ 10,493 $ 9,835 $ 10,493 $ 9,835 The change in fair value of the contingent consideration was primarily due to the impact of changes in interest rates, passage of time on the fair value measurement and the status of development of the underlying technology increases or decreases in any of the probabilities of success or changes in expected timelines for achievement of any of these milestones could result in a significantly higher or lower fair value of the liability. The fair value of the contingent consideration at each reporting date is updated by reflecting the changes in fair value in the Company’s consolidated statement of operations. There is no assurance that any of the conditions for the milestone payments will be met.

Property and Equipment

Property and Equipment	6 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Property and Equipment	Note 6. Property and Equipment The components of property and equipment are as follows: September 30, 2018 March 31, 2018 (in $000's) Land $ 7,408 $ 7,680 Building and building improvements 83,404 63,700 Leasehold improvements 2,180 2,905 Machinery and equipment 50,123 42,787 Furniture and fixtures 9,804 8,104 Construction in progress 14,026 19,850 Total cost 166,945 145,026 Less accumulated depreciation (32,880 ) (27,859 ) $ 134,065 $ 117,167

Goodwill In-Process Research an

Goodwill In-Process Research and Development and Other Assets	6 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill In-Process Research and Development and Other Assets	Note 7. Goodwill, In-Process Research and Development, and Other Assets</p> <p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-weight:bold;;font-size:6pt;"> </p> <p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">Goodwill</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The carrying amount of goodwill at September 30, 2018 and March 31, 2018 was $33.7 million and $35.8 million, respectively, and has been recorded in connection with the Company’s acquisition of Impella Cardiosystems AG, in May 2005 and ECP and AIS in July 2014. The goodwill activity is as follows:</p> <p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p> <div> <table border="0" cellspacing="0" cellpadding="0" align="center" style="border-collapse:collapse; width:60%;"> <tr> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:8pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td colspan="2" valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:16.82%; border-bottom:solid 0.75pt #000000;"> <p style="text-align:center;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;">(in $000's)</p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> </tr> <tr> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:80.22%;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at March 31, 2018</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1.94%;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000;white-space:nowrap;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">35,808</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> </tr> <tr> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Foreign currency translation impact</p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">(2,089</p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:solid 0.75pt transparent;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">)</p></td> </tr> <tr> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:double 2.5pt transparent;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at September 30, 2018</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:double 2.5pt transparent;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">33,719</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:double 2.5pt transparent;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:1pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> </tr> </table></div> <p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p> <p style="text-align:justify;margin-top:8pt;margin-bottom:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">In-Process Research & Development</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The Company evaluates goodwill and in-process research and development (“IPR&D”) assets at least annually at October 31, as well as whenever events or changes in circumstances suggest that the carrying amount may not be recoverable.  The Company has no accumulated impairment losses on goodwill or IPR&D assets.</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The carrying amount of IPR&D assets at September 30, 2018 and March 31, 2018 was $15.7 million and $16.7 million, respectively, and was recorded in conjunction with the Company’s acquisition of ECP and AIS, in July 2014. The estimated fair value of IPR&D assets at the acquisition date was determined using a probability-weighted income approach, which discounts expected future cash flows to present value. The projected cash flow estimates for the future Impella ECP<sup style="font-size:85%; vertical-align:top">TM</sup> expandable catheter pump technology were based on certain key assumptions, including estimates of future revenue and expenses, taking into account the stage of development of the technology at the acquisition date and the time and resources needed to complete development. The Company used an original discount rate of 21% and cash flows that have been probability adjusted to reflect the risks of product commercialization, which the Company believes are appropriate and representative of market participant assumptions.</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The carrying value of the Company’s IPR&D assets and the change in the balance for the six months ended September 30, 2018 are as follows:</p> <p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p> <div> <table border="0" cellspacing="0" cellpadding="0" align="center" style="border-collapse:collapse; width:60%;"> <tr> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:8pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td colspan="2" valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:16.82%; border-bottom:solid 0.75pt #000000;"> <p style="text-align:center;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;">(in $000's)</p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> </tr> <tr> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:80.22%;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at March 31, 2018</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1.94%;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000;white-space:nowrap;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">16,705</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> </tr> <tr> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Foreign currency translation impact</p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">(975</p></td> <td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:solid 0.75pt transparent;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">)</p></td> </tr> <tr> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:double 2.5pt transparent;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at September 30, 2018</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:double 2.5pt transparent;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> <p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">15,730</p></td> <td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:double 2.5pt transparent;white-space:nowrap;"> <p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:1pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;"> </p></td> </tr> </table></div> <p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;"> </p> <p style="margin-top:8pt;margin-bottom:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">Other Assets</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-weight:bold;font-style:italic;font-family:Times New Roman;font-size:10pt;text-transform:none;font-variant: normal;">Other Investments</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The Company periodically makes investments in private medical device companies that focus on heart failure, heart pump and other medical device technologies. The aggregate carrying amount of the Company’s other investments was $22.3 million and $12.6 million at September 30, 2018 and March 31, 2018, respectively, and is classified within other assets on the consolidated balance sheets. During the six months ended September 30, 2018, the Company made additional investments of $9.6 million in private medical device companies. </p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">On April 1, 2018, the Company adopted ASU 2016-01. <font style="Background-color:#FFFFFF;color:#000000;">This guidance requires equity investments to be measured at fair value with changes in fair value recognized in net income.  Since these investments do not have readily determinable market values, the Company has elected to measure these investments at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for an identical or similar investment.  No adjustments have been made to the value of the Company’s investments in these private medical device companies for the three and six months ended September 30, 2018 either due to impairment or based on observable price changes. The Company monitors any events or changes in circumstances that may have a significant adverse effect on the fair value of this investment and makes any necessary adjustments.</font></p> <p style="text-align:justify;margin-top:18pt;margin-bottom:0pt;text-indent:4.54%;font-weight:bold;font-style:italic;font-family:Times New Roman;font-size:10pt;text-transform:none;font-variant: normal;">Other Intangible Assets</p> <p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">In September 2018, the Company made a milestone payment to a third party for approximately $1.8 million for the transfer to the Company of manufacturing rights and knowledge for optical sensor technology that is approved for use in the Impella CP products.  This intangible asset is classified with other assets in the Company’s consolidated balance sheet will be amortized over the useful life of the intangible asset.</p></div>" id="sjs-B4">&lt;div> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">Note&#160;7. Goodwill, In-Process Research and Development, and Other Assets&lt;/p> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-weight:bold;;font-size:6pt;">&nbsp;&lt;/p> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">Goodwill&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The carrying amount of goodwill at September&#160;30, 2018 and March 31, 2018 was $33.7 million and $35.8 million, respectively, and has been recorded in connection with the Company&#8217;s acquisition of Impella Cardiosystems AG, in May 2005 and ECP and AIS in July 2014. The goodwill activity is as follows:&lt;/p> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&#160;&lt;/p> &lt;div> &lt;table border="0" cellspacing="0" cellpadding="0" align="center" style="border-collapse:collapse; width:60%;"> &lt;tr> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:8pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td colspan="2" valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:16.82%; border-bottom:solid 0.75pt #000000;"> &lt;p style="text-align:center;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;">(in $000's)&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;/tr> &lt;tr> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:80.22%;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at March 31, 2018&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1.94%;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">35,808&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;/tr> &lt;tr> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Foreign currency translation impact&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">(2,089&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:solid 0.75pt transparent;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">)&lt;/p>&lt;/td> &lt;/tr> &lt;tr> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:double 2.5pt transparent;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at September&#160;30, 2018&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:double 2.5pt transparent;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">33,719&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:double 2.5pt transparent;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:1pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;/tr> &lt;/table>&lt;/div> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&#160;&lt;/p> &lt;p style="text-align:justify;margin-top:8pt;margin-bottom:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">In-Process Research &amp; Development&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The Company evaluates goodwill and in-process research and development (&#8220;IPR&amp;D&#8221;) assets at least annually at October 31, as well as whenever events or changes in circumstances suggest that the carrying amount may not be recoverable.&nbsp;&nbsp;The Company has no accumulated impairment losses on goodwill or IPR&amp;D assets.&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The carrying amount of IPR&amp;D assets at September&#160;30, 2018 and March 31, 2018 was $15.7 million and $16.7 million, respectively, and was recorded in conjunction with the Company&#8217;s acquisition of ECP and AIS, in July 2014. The estimated fair value of IPR&amp;D assets at the acquisition date was determined using a probability-weighted income approach, which discounts expected future cash flows to present value. The projected cash flow estimates for the future Impella ECP&lt;sup style="font-size:85%; vertical-align:top">TM&lt;/sup> expandable catheter pump technology were based on certain key assumptions, including estimates of future revenue and expenses, taking into account the stage of development of the technology at the acquisition date and the time and resources needed to complete development. The Company used an original discount rate of 21% and cash flows that have been probability adjusted to reflect the risks of product commercialization, which the Company believes are appropriate and representative of market participant assumptions.&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The carrying value of the Company&#8217;s IPR&amp;D assets and the change in the balance for the six months ended September&#160;30, 2018 are as follows:&lt;/p> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&#160;&lt;/p> &lt;div> &lt;table border="0" cellspacing="0" cellpadding="0" align="center" style="border-collapse:collapse; width:60%;"> &lt;tr> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:8pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td colspan="2" valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:16.82%; border-bottom:solid 0.75pt #000000;"> &lt;p style="text-align:center;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;">(in $000's)&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;font-weight:bold;color:#000000;font-size:8pt;font-family:Times New Roman;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;/tr> &lt;tr> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:80.22%;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at March 31, 2018&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1.94%;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">16,705&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;/tr> &lt;tr> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:solid 0.75pt transparent;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Foreign currency translation impact&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:solid 0.75pt transparent;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-bottom:solid 0.75pt #000000;white-space:nowrap;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">(975&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#FFFFFF" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:solid 0.75pt transparent;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">)&lt;/p>&lt;/td> &lt;/tr> &lt;tr> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:80.22%; border-bottom:double 2.5pt transparent;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">Balance at September&#160;30, 2018&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1.94%; border-bottom:double 2.5pt transparent;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:1%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">$&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;padding-Bottom:0pt;width:15.82%; border-top:solid 0.75pt #000000; border-bottom:double 2.5pt #000000;white-space:nowrap;"> &lt;p style="text-align:right;margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">15,730&lt;/p>&lt;/td> &lt;td valign="bottom" bgcolor="#CFF0FC" style="padding-left:0pt;padding-Right:0.75pt;padding-Top:0.75pt;width:1%; border-bottom:double 2.5pt transparent;white-space:nowrap;"> &lt;p style="margin-bottom:0pt;margin-top:0pt;margin-left:0pt;;text-indent:0pt;;color:#000000;font-size:1pt;font-family:Times New Roman;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">&nbsp;&lt;/p>&lt;/td> &lt;/tr> &lt;/table>&lt;/div> &lt;p style="margin-bottom:0pt;margin-top:0pt;text-indent:0%;font-family:Times New Roman;font-size:10pt;">&nbsp;&lt;/p> &lt;p style="margin-top:8pt;margin-bottom:0pt;text-indent:0%;font-weight:bold;font-family:Times New Roman;font-size:10pt;font-style:normal;text-transform:none;font-variant: normal;">Other Assets&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-weight:bold;font-style:italic;font-family:Times New Roman;font-size:10pt;text-transform:none;font-variant: normal;">Other Investments&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">The Company periodically makes investments in private medical device companies that focus on heart failure, heart pump and other medical device technologies. The aggregate carrying amount of the Company&#8217;s other investments was $22.3 million and $12.6 million at September&#160;30, 2018 and March 31, 2018, respectively, and is classified within other assets on the consolidated balance sheets. During the six months ended September&#160;30, 2018, the Company made additional investments of $9.6 million in private medical device companies. &lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">On April 1, 2018, the Company adopted ASU 2016-01. &lt;font style="Background-color:#FFFFFF;color:#000000;">This guidance requires equity investments to be measured at fair value with changes in fair value recognized in net income.&#160;&#160;Since these investments do not have readily determinable market values, the Company has elected to measure these investments at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for an identical or similar investment.&#160;&#160;No&#160;adjustments have been made to the value of the Company&#8217;s investments in these private medical device companies for the&#160;three and six months ended&#160;September 30, 2018&#160;either due to impairment or based on observable price changes.&#160;The Company monitors any events or changes in circumstances that may have a significant adverse effect on the fair value of this investment and makes any necessary adjustments.&lt;/font>&lt;/p> &lt;p style="text-align:justify;margin-top:18pt;margin-bottom:0pt;text-indent:4.54%;font-weight:bold;font-style:italic;font-family:Times New Roman;font-size:10pt;text-transform:none;font-variant: normal;">Other Intangible Assets&lt;/p> &lt;p style="text-align:justify;margin-top:6pt;margin-bottom:0pt;text-indent:4.54%;font-family:Times New Roman;font-size:10pt;font-weight:normal;font-style:normal;text-transform:none;font-variant: normal;">In September 2018, the Company made a milestone payment to a third party for approximately $1.8 million for the transfer to the Company of manufacturing rights and knowledge for optical sensor technology that is approved for use in the Impella CP products.&nbsp;&nbsp;This intangible asset is classified with other assets in the Company&#8217;s consolidated balance sheet will be amortized over the useful life of the intangible asset.&lt;/p>&lt;/div>

Accrued Expenses

Accrued Expenses	6 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Accrued Expenses	Note 8. Accrued Expenses Accrued expenses consist of the following: September 30, 2018 March 31, 2018 (in $000's) Employee compensation $ 28,508 $ 30,330 Sales and income taxes 6,990 4,562 Marketing 3,001 2,305 Research & development 2,606 3,162 Professional, legal, and accounting fees 1,510 1,870 Warranty 1,160 1,081 Accrued capital expenditures — 250 Other 2,324 2,587 $ 46,099 $ 46,147 Employee compensation consists primarily of accrued bonuses, accrued commissions, accrued employee benefits, and accrued payroll taxes (on equity awards) at September 30, 2018 and March 31, 2018.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	Note 9. Stock-Based Compensation The following table summarizes stock-based compensation expense by financial statement line item in the Company’s consolidated statements of operations for the three and six months ended September 30, 2018 and 2017: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) Cost of product revenue $ 774 $ 372 $ 1,349 $ 731 Research and development 2,618 1,205 4,584 2,544 Selling, general and administrative 12,542 7,705 22,246 14,663 $ 15,934 $ 9,282 $ 28,179 $ 17,938 Stock Options The following table summarizes the stock option activity for the six months ended September 30, 2018: Weighted Weighted Average Aggregate Average Remaining Intrinsic Options Exercise Contractual Value (in thousands) Price Term (years) (in thousands) Outstanding at beginning of period 1,282 $ 46.18 5.31 Granted 76 383.96 Exercised (425 ) 24.95 Cancelled and expired (15 ) 153.17 Outstanding at end of period 918 $ 83.05 5.97 $ 331,490 Exercisable at end of period 669 $ 38.86 4.97 $ 271,255 Options vested and expected to vest at end of period 905 $ 82.85 5.94 $ 327,147 Stock options generally vest and become exercisable annually over three years. The remaining unrecognized stock-based compensation expense for unvested stock option awards at September 30, 2018 was approximately $15.8 million and the estimated weighted-average period over which this cost will be recognized is 2.3 years. The aggregate intrinsic value of options exercised was $155.4 million for the six months ended September 30, 2018. The total cash received as a result of employee stock options exercised during the six months ended September 30, 2018 was approximately $10.6 million. The Company estimates the fair value of each stock option granted at the grant date using the Black-Scholes option valuation model. The weighted average grant-date fair values and weighted average assumptions used in the calculation of fair value of options granted during the three and six months ended September 30, 2018 and 2017 was as follows: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Weighted average grant-date fair value $ 148.51 $ 57.38 $ 142.81 $ 50.26 Valuation assumptions: Risk-free interest rate 2.87 % 1.88 % 2.93 % 1.85 % Expected option life (years) 3.99 4.06 4.04 4.07 Expected volatility 43.9 % 43.4 % 42.7 % 43.6 % Restricted Stock Units The following table summarizes activity of restricted stock units for the six months ended September 30, 2018: Number of Shares Weighted Average Grant Date Fair Value (in thousands) (per share) Restricted stock units at beginning of period 880 $ 109.01 Granted 192 $ 379.63 Vested (404 ) $ 103.91 Forfeited (20 ) $ 187.41 Restricted stock units at end of period 649 $ 189.87 Restricted stock units generally vest annually over three years. The remaining unrecognized compensation expense for outstanding restricted stock units, including performance and market-based awards, as of September 30, 2018 was $72.1 million and the estimated weighted-average period over which this cost will be recognized is 2.3 years. The weighted average grant-date fair value for restricted stock units granted during the six months ended September 30, 2018 was $379.63. The total fair value of restricted stock units vested during the six months ended September 30, 2018 was $163.3 million. Performance-Based Awards In May 2018, performance-based awards of restricted stock units for the potential issuance of approximately 114,000 shares of common stock were issued to certain executive officers and employees, which vest upon achievement of prescribed service milestones by the award recipients and performance milestones by the Company. As of September 30, 2018, the Company is recognizing compensation expense based on the probable outcome related to the prescribed performance targets on the outstanding awards.

Income Taxes

Income Taxes	6 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 10. Income Taxes In December 2017, the Tax Cut and Jobs Act, (“Tax Reform Act”) was signed into law. The Tax Reform Act included significant changes to existing law, including among other items, a reduction to the U.S. federal statutory corporate tax rate from 35% to 21% effective January 1, 2018. ASC 740, Income Taxes (Topic 740) As a result of the Tax Reform Act, the Company’s U.S. federal statutory corporate income tax rate of 21% was applied in the computation of the income tax provision for the three and six months ended September 30, 2018 The Company’s income tax provision was $1.7 million for the three months ended September 30, 2018, the Company’s income tax benefit was $39.9 million for the six months ended September 30, 2018. The Company’s income tax provision was $8.0 million and $4.4 million for the three and six months ended September 30, 2017, respectively. The Company’s effective tax rate was 3.3% and (39.7)% for the three and six months ended September 30, 2018, respectively, and 24.6% and 6.6% for the three and six months ended September 30, 2017, respectively. Consistent with guidance issued by the SEC, which provides for a measurement period of one year from the enactment date to finalize the accounting for effects of the Tax Reform Act, the Company provisionally The Company recognizes excess tax benefits and shortfalls in the income tax provision as discrete items in the period when restricted stock units vest or stock option exercises occur, whereas previously such income tax effects were recorded as part of additional paid-in capital only when the related tax deduction resulted in a reduction of current income taxes payable. The Company recognized excess tax benefits associated with stock-based awards of $12.9 million and $66.8 million as an income tax benefit for the three and six months ended September 30, 2018, respectively, and $4.5 million and $21.3 million as an income tax benefit for the three and six months ended September 30, 2017, respectively. The amount of future excess tax benefits or shortfalls will likely fluctuate from period to period based on the price of the Company’s stock, the number of restricted stock units that vest or stock options that are exercised, and the fair value assigned to such stock-based awards under U.S. GAAP. The significant differences between the statutory income tax rate and effective income tax rate for the three and six months ended September 30, 2018 and 2017 consist of the following items: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Statutory income tax rate 21.0 % 35.0 % 21.0 % 35.0 % Increase resulting from: Excess tax benefits from stock-based awards (24.9 ) (13.7 ) (66.6 ) (32.1 ) Credits (1.8 ) (1.2 ) (1.8 ) (1.2 ) State taxes, net 4.3 3.5 4.3 3.5 Permanent differences 1.8 1.8 1.8 1.8 Other 2.9 (0.8 ) 1.6 (0.4 ) Effective tax rate 3.3 % 24.6 % (39.7 ) % 6.6 % The recently enacted Tax Reform Act allows for a 100% deduction for the potential repatriation of foreign subsidiary earnings with minimal U.S. income tax consequences other than the one-time deemed repatriation toll charge The Company and its subsidiaries are subject to U.S. federal income tax, as well as income tax of multiple state and foreign jurisdictions. During the six months ended September 30, 2018, the Company closed an income tax audit in Germany which covered fiscal years 2012 through 2015. The audit resulted in an immaterial adjustment to our financial statements. Fiscal years 2016 through 2018 remain open to examination in Germany. The Company also closed an Internal Revenue Service (“IRS”) audit relating to its fiscal year 2016 tax return. The audit resulted in an immaterial adjustment to our financial statements. All other tax years remain subject to examination by the IRS, state and foreign tax authorities.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 11. Commitments and Contingencies Commitments Leases In February 2017, the Company entered into a lease agreement for 21,603 square feet of office space in Danvers, Massachusetts expiring on July 31, 2022. In December 2017, the Company entered into an amendment to this lease to extend the term through August 31, 2025 and to add an additional 6,607 square feet of space for which rent began on June 1, 2018. In March 2018, the Company entered into a second amendment to the lease to add an additional 11,269 square feet of space. In July 2018, the Company entered into an amendment to lease an additional 23,864 square feet of space from October 1, 2018 through September 30, 2027. With this most recent amendment, the Company has leased 63,343 square feet in total at this location as of October 1, 2018. The Company also has a right of first offer to purchase the property from January 1, 2018 through August 31, 2035, if the lessor decides to sell the building. The annual rent expense for the lease is estimated to be $0.9 million. In September 2016, the Company entered into a lease agreement for an office in Berlin, Germany which commenced in May 2017 and expires in May 2024. The annual rent expense for the lease is estimated to be $0.3 million. In October 2016, t he Company entered into a lease agreement for an office in Tokyo, Japan which expires in September 2021. The office houses administrative, regulatory, and training personnel in connection with the Company’s commercial launch in Japan. The annual rent expense for the lease is estimated to be $0.9 million. 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, or Thoratec, a subsidiary of Abbott Laboratories, has challenged a number of Company-owned patents in Europe in connection with the launch of its HeartMate PHP medical device, or PHP, in Europe. These actions relate to Thoratec’s ability to manufacture and sell its PHP product in Europe. These actions do not relate to the Company’s ability to manufacture or sell its Impella line of devices. In December 2014, Thoratec filed a nullity suit in the German Federal Patent Court against a German “pigtail” patent owned by the Company with a flexible extension feature, and auxiliary pigtail, basket and funnel features. The validity hearing was held in November 2016 and the Federal Patent Court found the patent invalid. The Company is appealing this decision. In August 2015, Thoratec filed a nullity action in the German Federal Patent Court against two Company-owned patents covering a “magnetic clutch” feature. These magnetic clutch patents were acquired by the Company in July 2014, in connection with its acquisition of ECP and AIS. The validity hearing for the magnetic clutch patents was held in June 2017. The Company’s patents were upheld in an amended form to focus on the structure and interaction of the magnets in the clutch. The Federal Patent Court found certain unamended claims to be invalid. The Company is appealing the decision with respect to the unamended claims. In September 2015, the Company filed counterclaims in the magnetic clutch action in Germany asserting that the PHP product infringes the two magnetic clutch patents, a European pigtail patent and the German pigtail patent. The infringement trial has been stayed, pending resolution of the German nullity actions. In February 2017, Thoratec filed an opposition in the European Patent Office (“EPO”), against a Company-owned patent acquired in connection with the acquisition of ECP and AIS relating to a housing structure for an expandable pump. The Company filed an initial response to the opposition in July 2017. Oral proceedings were held on October 26, 2018, at which time the EPO revoked the patent. A written decision documenting the reasons for the revocation is expected to issue within a few months, after which the Company may file an appeal. In December 2017, Thoratec filed an opposition in the EPO against a Company-owned patent acquired in connection with the acquisition of ECP and AIS relating to a pump having a shaft cap with an atraumatic ball. The Company responded to the opposition on May 27, 2018 and is awaiting a preliminary opinion from the EPO Opposition Division. Maquet Matters In December 2015, the Company received a letter from Maquet Cardiovascular LLC, or Maquet, a subsidiary of the Getinge Group, asserting that the Company’s Impella devices infringe certain claims having guidewire, lumen and sensor features, which were in two Maquet patents and one pending patent application in the U.S. and elsewhere, and attached a draft litigation complaint and encouraged the Company to take a license from Maquet. In January 2016, the Company responded to Maquet stating that it believed that the cited claims were invalid and that its Impella devices did not infringe the cited patents. In May 2016, Maquet notified the Company that its pending U.S. patent application had been issued as a U.S. patent, repeated their earlier assertion and encouraged the Company to discuss taking a license from Maquet. The three patents expire September 2020, December 2020 and October 2021. In May 2016, the Company filed suit in U.S. District Court for the District of Massachusetts (“D. Mass.”) against Maquet seeking a declaratory judgment that the Company’s Impella devices do not infringe Maquet’s cited patent rights. In August 2016, Maquet sent a letter to the Company identifying four new U.S. continuation patent filings with claims that Maquet alleges are infringed by the Company’s Impella devices. Of the four U.S. continuation applications, one issued as a patent on January 17, 2017, one issued as a patent on February 7, 2017, one issued as a patent on March 21, 2017, and one issued as a patent on October 17, 2017. These four issued patents 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”). On June 15, 2017, Maquet filed a motion for leave to amend its infringement counterclaims to add the first three additional U.S. continuation patents mentioned above and to file various false advertising, unfair competition claims under state law and under the Lanham Act, and a trademark cancellation in the pending case. Maquet’s amended complaint and counterclaim, like those it originally filed, seek injunctive relief and monetary damages in the form of a reasonable royalty, with three times the amount for alleged willful infringement. The amended complaint admits that Maquet’s current commercially available products do not embody the claims of the asserted patents. On July 21, 2017, the Court granted the motion in part, allowing the three additional continuation patents to be added to the case, but denying addition of the false advertising claims, Lanham Act claims, and the trademark cancellation claims. On April 24 and 25, 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. A hearing was held on November 2, 2018 to re-hear arguments on one of the terms. Discovery remains ongoing. No schedule has yet been set for the remainder of the case. With regard to the first six Maquet patents mentioned above, in March and April 2017, the Company filed requests for inter partes review, (“IPR”), at the U.S. Patent & Trademark Office’s Patent Trial and Appeals Board (“PTAB”) asserting that the claims are invalid in view of prior art blood pump technology. In September and October 2017, the PTAB denied institution on these IPR requests filed by the Company. In September 2017, the Company filed additional IPRs and in March and April 2018, the PTAB denied institution of these IPR petitions. On November 22, 2017, Maquet filed a second lawsuit in D. Mass 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). In the complaint, 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 answer to ABIOMED’s counterclaim, Maquet admits that its current commercially available products do not embody the claims of the asserted patents. This second action is in its early stages. 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 Marquet and Thoratec patent disputes.

Segment and Enterprise Wide Dis

Segment and Enterprise Wide Disclosures	6 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment and Enterprise Wide Disclosures	Note 12. Segment and Enterprise Wide Disclosures The Company operates in one business segment—the research, development and sale of medical devices to assist or replace the pumping function of the failing heart. The Company’s chief operating decision maker (determined to be the Chief Executive Officer) does not manage any part of the Company separately, and the allocation of resources and assessment of performance are based on the Company’s consolidated operating results. International sales (sales outside the U.S., primarily in Europe and Japan) accounted for 13% or total revenue for each of the three and six months ended September 30, 2018, respectively, and 11% and 10% of total revenue for the three and six months ended September 30, 2017, respectively. T he Company’s long-lived assets are located in the U.S. except for $39.4 million and $35.5 million at September 30, 2018 and March 31, 2018, respectively, which are located primarily in Germany.

Basis of Preparation and Summ_2

Basis of Preparation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
New Accounting Pronouncements Adopted	New Accounting Pronouncements Adopted Effective April 1, 2018, the Company adopted the Financial Accounting Standards Board (“FASB”) standard update ASU 2014-09, “Revenue from Contracts with Customers,” (“Topic 606”) which provides a principles-based, five-step approach to measure and recognize revenue from contracts with customers. The adoption of this guidance did not have a material impact on the Company’s consolidated statement of operations, cash flows, and balance sheet as of the adoption date or for the three or six months ended September 30, 2018. Additional information and disclosures required by this new standard are contained in “Note 4. Revenue Recognition,” to the Company’s consolidated financial statements. Effective April 1, 2018, the Company adopted the FASB standard update ASU 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities,” which requires certain financial assets to be measured at fair value with changes in fair value recognized in the statement of operations. The adoption of this guidance did not have a material impact on the Company’s consolidated statement of operations, cash flows, and balance sheet as of the adoption date or for the three or six months ended September 30, 2018. Additional information and disclosures required by this new standard are contained in “Note 5. Cash Equivalents, Marketable Securities, and Fair Value Measurements,” to the Company’s consolidated financial statements. On June 20, 2018, the FASB issued ASU 2018-07, “Compensation – Stock Compensation (“Topic 718”): Improvements to Nonemployee Share-Based Payment Accounting,” which simplifies the accounting for share-based payments granted to nonemployees for goods and services. ASU 2018-07 eliminated the previous guidance for accounting for share-based payments to nonemployees and expanded Topic 718 to include share-based payments transactions to nonemployees. ASU 2018-07 is effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted, but no earlier than an entity’s adoption date of Topic 606. The adoption of ASU 2018-07 requires a modified retrospective transition approach, with a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year. The Company early adopted ASU 2018-07 on June 20, 2018. The adoption of this guidance did not have a material impact on the Company’s consolidated statements of operations, cash flows, and balance sheet as of the adoption date or for the three or six months ended September 30, 2018.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, “Leases.” The new guidance significantly impacts lessee accounting and financial statement disclosures. Specifically, this guidance requires lessees to identify arrangements that should be accounted for as leases. Under this guidance, for lease arrangements exceeding a one year term, a right-of-use asset and lease obligation is recorded by the lessee for all leases on the balance sheet, whether operating or financing, while the statement of operations includes lease expense for operating leases and amortization and interest expense for financing leases. The lease obligation amount recorded on the balance sheet at the date of adoption of this guidance must be calculated using the applicable incremental borrowing rate at the date of adoption. Leases with a term of one year or less will be accounted for similar to existing guidance for operating leases. The Company is currently in the process of evaluating its lease arrangements to determine the impact of ASU 2016-02 on its consolidated financial statements as well as updating processes and controls in order to adopt the new standard. This evaluation includes a review of the Company’s existing leasing arrangements on its facilities. In addition, the evaluation includes a review of the Company’s existing contracts with its suppliers and vendors to determine if these agreements contain an embedded lease. The Company currently expects that its lease commitments will be recognized as operating lease liabilities and right-of-use assets upon adoption, which will increase total assets and total liabilities that the Company reports on its consolidated balance sheet. ASU 2016-02 must be adopted using a modified retrospective approach for all leases existing at, or entered into after the date of initial adoption, with an option to elect to use certain transition relief. ASU 2016-02 will become effective for the Company on April 1, 2019.
Adoption of Topic 606, Revenue from Contracts with Customers	Adoption of Topic 606, Revenue from Contracts with Customers The Company adopted Topic 606 on April 1, 2018, using the modified retrospective method for all contracts not completed as of the date of adoption. The reported results for fiscal year 2019 reflect the application of Topic 606 guidance while the reported results for fiscal year 2018 were prepared under the guidance of ASC 605, “Revenue Recognition.” The adoption of Topic 606 did not have a material impact on the timing or amount of revenue recognized upon adoption and there was no cumulative prior period adjustment recorded to the opening balance of retained earnings upon adoption. Accordingly, the adoption of Topic 606 did not have a material impact on the Company’s consolidated balance sheet, statement of operations, stockholders’ equity or cash flows as of the adoption date or for the three or six months ended September 30, 2018. The Company has made the following accounting policy elections and elected to use certain practical expedients, as permitted by the FASB, in applying Topic 606: (1) the Company accounts for amounts collected from customers for sales and other taxes, net of related amounts remitted to tax authorities; (2) the Company does not adjust the promised amount of consideration for the effects of a significant financing component because, at contract inception, the Company expects the period between the time when the Company transfers a promised good or service to the customer and the time when the customer pays for that good or service will be one year or less; (3) the Company expenses costs to obtain a contract as they are incurred if the expected period of benefit, and therefore the amortization period, is one year or less; (4) the Company accounts for shipping and handling activities that occur after control transfers to the customer as a fulfillment cost rather than an additional promised service and these fulfillment costs are recorded as selling, general and administrative expenses; (5) the Company does not assess whether promised goods or services are performance obligations if they are immaterial in the context of the contract with the customer; and (6) the Company does not disclose the transaction price allocated to unsatisfied performance obligations when the original expected contract duration is one year or less. The Company generates revenue primarily from the sale of Impella 2.5, Impella CP, Impella 5.0, Impella LD, Impella RP and Impella AIC products. The Company also generates revenue from preventative maintenance service contracts and maintenance calls. The Company determines revenue recognition through the following steps: • Identification of the contract, or contracts, with a customer • Identification of the performance obligation in the contract • Determination of the transaction price • Allocation of the transaction price to the performance obligation in the contract • Recognition of revenue when, or as, a performance obligation is satisfied

Net Income Per Share (Tables)

Net Income Per Share (Tables)	6 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Income Per Share	The Company’s basic and diluted net income per share for the three and six months ended September 30, 2018 and 2017 were as follows (in thousands, except per share data): For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Basic Net Income Per Share Net income $ 50,127 $ 24,503 $ 140,193 $ 61,877 Basic weighted average shares outstanding 44,961 44,141 44,754 44,018 Basic net income per share $ 1.11 $ 0.56 $ 3.13 $ 1.41 For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Diluted Net Income Per Share Net income $ 50,127 $ 24,503 $ 140,193 $ 61,877 Basic weighted average shares outstanding 44,961 44,141 44,754 44,018 Effect of dilutive securities 1,192 1,557 1,410 1,637 Diluted weighted average shares outstanding 46,153 45,698 46,164 45,655 Diluted net income per share $ 1.09 $ 0.54 $ 3.04 $ 1.36

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Sep. 30, 2018
Revenue Recognition And Deferred Revenue [Abstract]
Schedule of Disaggregated Revenue by Major Business Line and Geographical Location	The following table disaggregates the Company’s revenue by products and services: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) Impella product revenue $ 175,270 $ 127,400 $ 348,945 $ 254,594 Service and other revenue 6,508 5,423 12,843 10,697 Total revenue $ 181,778 $ 132,823 $ 361,788 $ 265,291 The following table disaggregates the Company’s revenue by geographical location: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) U.S. revenue $ 158,243 $ 118,669 $ 315,838 $ 238,335 International revenue 23,535 14,154 45,950 26,956 Total revenue $ 181,778 $ 132,823 $ 361,788 $ 265,291
Summary of Activity in Each of Product Revenue and Discounts Categories	The following table summarizes product revenue rebates and discounts for the six months ended September 30, 2018 (in thousands): Rebates and Discounts Balance at March 31, 2018 $ 1,405 Provision related to current period revenue 989 Credits and adjustments made during the period (869 ) Balance at September 30, 2018 $ 1,525

Cash Equivalents, Marketable Se

Cash Equivalents, Marketable Securities and Fair Value Measurements (Tables)	6 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Cash Equivalents and Marketable Securities by Balance Sheet Classification	The Company’s cash equivalents and marketable securities at September 30, 2018 and March 31, 2018 are classified on the balance sheet as follows: September 30, 2018 March 31, 2018 (in $000's) Cash equivalents $ 17,768 $ 22,595 Short-term marketable securities 334,064 319,274 Long-term marketable securities — 37,502 $ 351,832 $ 379,371
Cash Equivalents and Marketable Securities	The Company’s cash equivalents and marketable securities at September 30, 2018 and March 31, 2018 are invested in the following: Amortized Gross Unrealized Gross Unrealized Fair Market Cost Gains Losses Value (in $000's) September 30, 2018: Money market funds $ 17,768 $ — $ — $ 17,768 Short-term U.S. Treasury mutual fund securities 39,729 — (63 ) 39,666 Short-term government-backed securities 204,018 — (349 ) 203,669 Short-term corporate debt securities 54,477 — (54 ) 54,423 Short-term commercial paper 36,326 — (20 ) 36,306 $ 352,318 $ — $ (486 ) $ 351,832 Amortized Gross Unrealized Gross Unrealized Fair Market Cost Gains Losses Value (in $000's) March 31, 2018: Money market funds $ 5,845 $ — $ — $ 5,845 Repurchase agreements 16,750 — — 16,750 Short-term U.S. Treasury mutual fund securities 18,132 — (29 ) 18,103 Short-term government-backed securities 212,255 3 (538 ) 211,720 Short-term corporate debt securities 52,737 — (161 ) 52,576 Short-term commercial paper 36,936 2 (63 ) 36,875 Long-term U.S. Treasury mutual fund securities 10,953 — (16 ) 10,937 Long-term government-backed securities 24,798 1 (12 ) 24,787 Long-term corporate debt securities 1,777 1 — 1,778 $ 380,183 $ 7 $ (819 ) $ 379,371
Financial Instruments Recorded at Fair Value	The following table presents the Company’s financial instruments recorded at fair value in the consolidated balance sheets, classified according to the three categories described above: Level 1 Level 2 Level 3 Total September 30, 2018: (in $000's) Assets Money market funds $ 17,768 $ — $ — $ 17,768 Short-term U.S. Treasury mutual fund securities — 39,666 — 39,666 Short-term government-backed securities — 203,669 — 203,669 Short-term corporate debt securities — 54,423 — 54,423 Short-term commercial paper — 36,306 — 36,306 Liabilities Contingent consideration — — 10,493 10,493 Level 1 Level 2 Level 3 Total March 31, 2018: (in $000's) Assets Money market funds $ 5,845 $ — $ — $ 5,845 Repurchase agreements — 16,750 — 16,750 Short-term U.S. Treasury mutual fund securities — 18,103 — 18,103 Short-term government-backed securities — 211,720 — 211,720 Short-term corporate debt securities — 52,576 — 52,576 Short-term commercial paper — 36,875 — 36,875 Long-term U.S. Treasury mutual fund securities — 10,937 — 10,937 Long-term government-backed securities — 24,787 — 24,787 Long-term corporate debt securities — 1,778 — 1,778 Liabilities Contingent consideration — — 10,490 10,490
Valuation Method Used to Calculate Level 3 Liabilities Measured at Estimated Fair Value of Contingent Consideration Related to Acquisition	This liability is reported as Level 3 as the estimated fair value of the contingent consideration related to the acquisition of ECP requires significant management judgment or estimation and is calculated using the following valuation methods: Milestone Payment Fair Value at September 30, 2018 (in $000's) Valuation Methodology Significant Unobservable Input Weighted Average (range, if applicable) Clinical and regulatory milestone $ 7,000 $ 5,767 Probability weighted income approach Projected fiscal year of milestone payments 2019 to 2022 Discount rate 3.9% to 4.2% Probability of occurrence Probability adjusted level of 40% for the base case scenario and 10% to 40% for various upside and downside scenarios Revenue-based milestone 8,000 4,726 Monte Carlo simulation model Projected fiscal year of milestone payments 2024 to 2035 Discount rate 15% Expected volatility for forecasted revenues 50% Probability of payment 79% $ 15,000 $ 10,493
Change in Fair Value of Contingent Consideration as Determined by Level 3 Inputs	The following table summarizes the change in fair value, as determined by Level 3 inputs, of the contingent consideration for the three and six months ended September 30, 2018 and 2017: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) Level 3 liabilities, beginning balance $ 10,331 $ 9,418 $ 10,490 $ 9,153 Additions — — — — Payments — — — — Change in fair value 162 417 3 682 Level 3 liabilities, ending balance $ 10,493 $ 9,835 $ 10,493 $ 9,835

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Components of Property and Equipment	The components of property and equipment are as follows: September 30, 2018 March 31, 2018 (in $000's) Land $ 7,408 $ 7,680 Building and building improvements 83,404 63,700 Leasehold improvements 2,180 2,905 Machinery and equipment 50,123 42,787 Furniture and fixtures 9,804 8,104 Construction in progress 14,026 19,850 Total cost 166,945 145,026 Less accumulated depreciation (32,880 ) (27,859 ) $ 134,065 $ 117,167

Goodwill In-Process Research _2

Goodwill In-Process Research and Development and Other Assets (Tables)	6 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill Activity	The goodwill activity is as follows: (in $000's) Balance at March 31, 2018 $ 35,808 Foreign currency translation impact (2,089 ) Balance at September 30, 2018 $ 33,719
Carrying value of In-Process Research and Development	The carrying value of the Company’s IPR&D assets and the change in the balance for the six months ended September 30, 2018 are as follows: (in $000's) Balance at March 31, 2018 $ 16,705 Foreign currency translation impact (975 ) Balance at September 30, 2018 $ 15,730

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Accrued Expenses	Accrued expenses consist of the following: September 30, 2018 March 31, 2018 (in $000's) Employee compensation $ 28,508 $ 30,330 Sales and income taxes 6,990 4,562 Marketing 3,001 2,305 Research & development 2,606 3,162 Professional, legal, and accounting fees 1,510 1,870 Warranty 1,160 1,081 Accrued capital expenditures — 250 Other 2,324 2,587 $ 46,099 $ 46,147

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Recognized	The following table summarizes stock-based compensation expense by financial statement line item in the Company’s consolidated statements of operations for the three and six months ended September 30, 2018 and 2017: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 (in $000's) (in $000's) Cost of product revenue $ 774 $ 372 $ 1,349 $ 731 Research and development 2,618 1,205 4,584 2,544 Selling, general and administrative 12,542 7,705 22,246 14,663 $ 15,934 $ 9,282 $ 28,179 $ 17,938
Summary of Stock Option Activity	The following table summarizes the stock option activity for the six months ended September 30, 2018: Weighted Weighted Average Aggregate Average Remaining Intrinsic Options Exercise Contractual Value (in thousands) Price Term (years) (in thousands) Outstanding at beginning of period 1,282 $ 46.18 5.31 Granted 76 383.96 Exercised (425 ) 24.95 Cancelled and expired (15 ) 153.17 Outstanding at end of period 918 $ 83.05 5.97 $ 331,490 Exercisable at end of period 669 $ 38.86 4.97 $ 271,255 Options vested and expected to vest at end of period 905 $ 82.85 5.94 $ 327,147
Summary of Weighted Average Grant-Date Fair Values And Weighted Average Assumptions Used to Calculate Fair Value of Options Granted	The weighted average grant-date fair values and weighted average assumptions used in the calculation of fair value of options granted during the three and six months ended September 30, 2018 and 2017 was as follows: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Weighted average grant-date fair value $ 148.51 $ 57.38 $ 142.81 $ 50.26 Valuation assumptions: Risk-free interest rate 2.87 % 1.88 % 2.93 % 1.85 % Expected option life (years) 3.99 4.06 4.04 4.07 Expected volatility 43.9 % 43.4 % 42.7 % 43.6 %
Summary of Restricted Stock Units Activity	The following table summarizes activity of restricted stock units for the six months ended September 30, 2018: Number of Shares Weighted Average Grant Date Fair Value (in thousands) (per share) Restricted stock units at beginning of period 880 $ 109.01 Granted 192 $ 379.63 Vested (404 ) $ 103.91 Forfeited (20 ) $ 187.41 Restricted stock units at end of period 649 $ 189.87

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Differences Between Statutory Income Tax Rate and Effective Income Tax Rate	The significant differences between the statutory income tax rate and effective income tax rate for the three and six months ended September 30, 2018 and 2017 consist of the following items: For the Three Months Ended September 30, For the Six Months Ended September 30, 2018 2017 2018 2017 Statutory income tax rate 21.0 % 35.0 % 21.0 % 35.0 % Increase resulting from: Excess tax benefits from stock-based awards (24.9 ) (13.7 ) (66.6 ) (32.1 ) Credits (1.8 ) (1.2 ) (1.8 ) (1.2 ) State taxes, net 4.3 3.5 4.3 3.5 Permanent differences 1.8 1.8 1.8 1.8 Other 2.9 (0.8 ) 1.6 (0.4 ) Effective tax rate 3.3 % 24.6 % (39.7 ) % 6.6 %

Computation of Basic and Dilute

Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic Net Income Per Share
Net income	$ 50,127	$ 24,503	$ 140,193	$ 61,877
Basic weighted average shares outstanding	44,961	44,141	44,754	44,018
Basic net income per share	$ 1.11	$ 0.56	$ 3.13	$ 1.41
Diluted Net Income Per Share
Net income	$ 50,127	$ 24,503	$ 140,193	$ 61,877
Basic weighted average shares outstanding	44,961	44,141	44,754	44,018
Effect of dilutive securities	1,192	1,557	1,410	1,637
Diluted weighted average shares outstanding	46,153	45,698	46,164	45,655
Diluted net income per share	$ 1.09	$ 0.54	$ 3.04	$ 1.36

Net Income Per Share - Addition

Net Income Per Share - Additional Information (Detail) - shares	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of diluted weighted average shares outstanding	4,000	200	54,000	5,700
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of diluted weighted average shares outstanding	97,000	77,000	97,000	77,000

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Detail) - USD ($)	Apr. 01, 2018	Sep. 30, 2018	Sep. 30, 2018	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Contract with customer payment terms, description			Payment terms vary by contract type and type of customer and generally range from 30 to 60 days for direct sales customers. Payment terms with certain international distributors can be up to 90 days. The Company’s contracts with customers do not typically include extended payment terms.
Deferred revenue		$ 13,996,000	$ 13,996,000	$ 14,970,000
Deferred Revenue, Revenue Recognized		$ 3,300,000	$ 12,400,000
Minimum
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers, performance obligation term		1 year	1 year
Minimum | Direct Sales Customers
Disaggregation Of Revenue [Line Items]
Contract with customer payment terms, period			30 days
Maximum | Direct Sales Customers
Disaggregation Of Revenue [Line Items]
Contract with customer payment terms, period			60 days
Maximum | International Distributors
Disaggregation Of Revenue [Line Items]
Contract with customer payment terms, period			90 days
Accounting Standards Update 2014-09
Disaggregation Of Revenue [Line Items]
Cumulative prior period adjustment recorded to opening balance of retained earnings	$ 0

Revenue Recognition - Schedule

Revenue Recognition - Schedule of Disaggregated Revenue by Major Business Line (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 181,778	$ 132,823	$ 361,788	$ 265,291
Impella Product
Disaggregation Of Revenue [Line Items]
Total revenue	175,270	127,400	348,945	254,594
Service and Other
Disaggregation Of Revenue [Line Items]
Total revenue	$ 6,508	$ 5,423	$ 12,843	$ 10,697

Revenue Recognition - Schedul_2

Revenue Recognition - Schedule of Disaggregated Revenue by Major Geographical Location (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 181,778	$ 132,823	$ 361,788	$ 265,291
U.S.
Disaggregation Of Revenue [Line Items]
Total revenue	158,243	118,669	315,838	238,335
International
Disaggregation Of Revenue [Line Items]
Total revenue	$ 23,535	$ 14,154	$ 45,950	$ 26,956

Revenue Recognition - Summary o

Revenue Recognition - Summary of Activity in Each of Product Revenue and Discounts Categories (Detail) $ in Thousands	6 Months Ended
	Sep. 30, 2018USD ($)
Revenue Recognition And Deferred Revenue [Abstract]
Balance at March 31, 2018	$ 1,405
Provision related to current period revenue	989
Credits and adjustments made during the period	(869)
Balance at September 30, 2018	$ 1,525

Cash Equivalents and Marketable

Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Cash equivalents	$ 17,768	$ 22,595
Short-term marketable securities	334,064	319,274
Long-term marketable securities		37,502
Available-for-sale securities, fair value disclosure	$ 351,832	$ 379,371

Investable Cash Equivalents and

Investable Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 352,318	$ 380,183
Gross Unrealized Gains		7
Gross Unrealized Losses	(486)	(819)
Fair Market Value	351,832	379,371
Repurchase Agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		16,750
Fair Market Value		16,750
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	17,768	5,845
Fair Market Value	17,768	5,845
Commercial Paper | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	36,326	36,936
Gross Unrealized Gains		2
Gross Unrealized Losses	(20)	(63)
Fair Market Value	36,306	36,875
U.S. Treasury mutual fund securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	39,729	18,132
Gross Unrealized Losses	(63)	(29)
Fair Market Value	39,666	18,103
U.S. Treasury mutual fund securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		10,953
Gross Unrealized Losses		(16)
Fair Market Value		10,937
Government-backed securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	204,018	212,255
Gross Unrealized Gains		3
Gross Unrealized Losses	(349)	(538)
Fair Market Value	203,669	211,720
Government-backed securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		24,798
Gross Unrealized Gains		1
Gross Unrealized Losses		(12)
Fair Market Value		24,787
Corporate Debt Securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	54,477	52,737
Gross Unrealized Losses	(54)	(161)
Fair Market Value	$ 54,423	52,576
Corporate Debt Securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		1,777
Gross Unrealized Gains		1
Fair Market Value		$ 1,778

Financial Instruments Recorded

Financial Instruments Recorded at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	$ 351,832	$ 379,371
Contingent consideration	10,493	10,490
Repurchase Agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		16,750
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	17,768	5,845
Commercial Paper | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	36,306	36,875
Level 1 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	17,768	5,845
Level 2 | Repurchase Agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		16,750
Level 2 | Commercial Paper | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	36,306	36,875
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	10,493	10,490
U.S. Treasury mutual fund securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	39,666	18,103
U.S. Treasury mutual fund securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		10,937
U.S. Treasury mutual fund securities | Level 2 | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	39,666	18,103
U.S. Treasury mutual fund securities | Level 2 | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		10,937
Government-backed securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	203,669	211,720
Government-backed securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		24,787
Government-backed securities | Level 2 | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	203,669	211,720
Government-backed securities | Level 2 | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		24,787
Corporate Debt Securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	54,423	52,576
Corporate Debt Securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		1,778
Corporate Debt Securities | Level 2 | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	$ 54,423	52,576
Corporate Debt Securities | Level 2 | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure		$ 1,778

Cash Equivalents, Marketable _2

Cash Equivalents, Marketable Securities and Fair Value Measurements - Additional Information (Detail) - ECP Entwicklungsgesellschaft mbH $ in Millions	1 Months Ended
	Jul. 31, 2014USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payments to acquire businesses, cash paid	$ 13
Potential payouts payments	$ 15

Valuation Method Used to Calcul

Valuation Method Used to Calculate Level 3 Liabilities Measured at Estimated Fair Value of Contingent Consideration Related to Acquisition (Detail) $ in Thousands	6 Months Ended
	Sep. 30, 2018USD ($)	Mar. 31, 2018USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 10,493	$ 10,490
ECP Entwicklungsgesellschaft mbH | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	21
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 10,493	$ 10,490
Level 3 | ECP Entwicklungsgesellschaft mbH
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Milestone Payment	15,000
Contingent consideration	10,493
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Milestone Payment	7,000
Contingent consideration	$ 5,767
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Base Case Scenario | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of occurrence	40.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Minimum | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2,019
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Minimum | Various Upside and Downside Scenarios | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of occurrence	10.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Maximum | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2,022
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Maximum | Various Upside and Downside Scenarios | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of occurrence	40.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Discount Rate | Minimum | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	3.9
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Discount Rate | Maximum | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	4.2
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Milestone Payment	$ 8,000
Contingent consideration	$ 4,726
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of payment	79.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Minimum | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2,024
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Maximum | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2,035
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Discount Rate | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	15
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Expected Volatility for Forecasted Revenues | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	50

Change in Fair Value of Conting

Change in Fair Value of Contingent Consideration as Determined by Level 3 Inputs (Detail) - Contingent Consideration - ECP Entwicklungsgesellschaft mbH - Level 3 - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3 liabilities, beginning balance	$ 10,331	$ 9,418	$ 10,490	$ 9,153
Additions	0	0	0	0
Payments	0	0	0	0
Change in fair value	162	417	3	682
Level 3 liabilities, ending balance	$ 10,493	$ 9,835	$ 10,493	$ 9,835

Components of Property and Equi

Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Property Plant And Equipment [Abstract]
Land	$ 7,408	$ 7,680
Building and building improvements	83,404	63,700
Leasehold improvements	2,180	2,905
Machinery and equipment	50,123	42,787
Furniture and fixtures	9,804	8,104
Construction in progress	14,026	19,850
Total cost	166,945	145,026
Less accumulated depreciation	(32,880)	(27,859)
Property and equipment, net	$ 134,065	$ 117,167

Goodwill In-Process Research _3

Goodwill In-Process Research and Development and Other Assets - Additional Information (Detail)	1 Months Ended	6 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Mar. 31, 2018USD ($)
Goodwill [Line Items]
Goodwill	$ 33,719,000	$ 33,719,000	$ 35,808,000
Accumulated impairment loss, goodwill	0	0
In-process research and development	15,730,000	15,730,000	16,705,000
Aggregate carrying amount of other investments	22,300,000	22,300,000	12,600,000
Other additional Investments in private medical device company		9,600,000
Manufacturing Rights and Knowledge
Goodwill [Line Items]
Milestone Payment	1,800,000
ECP Entwicklungsgesellschaft mbH
Goodwill [Line Items]
In-process research and development	$ 15,700,000	$ 15,700,000	$ 16,700,000
ECP Entwicklungsgesellschaft mbH | Discount Rate
Goodwill [Line Items]
Fair value measurement inputs	21	21

Goodwill Activity (Detail)

Goodwill Activity (Detail) $ in Thousands	6 Months Ended
	Sep. 30, 2018USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance	$ 35,808
Foreign currency translation impact	(2,089)
Ending balance	$ 33,719

Carrying value of In-Process Re

Carrying value of In-Process Research and Development (Detail) $ in Thousands	6 Months Ended
	Sep. 30, 2018USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance	$ 16,705
Foreign currency translation impact	(975)
Ending balance	$ 15,730

Accrued Expenses (Detail)

Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Payables and Accruals [Abstract]
Employee compensation	$ 28,508	$ 30,330
Sales and income taxes	6,990	4,562
Marketing	3,001	2,305
Research & development	2,606	3,162
Professional, legal, and accounting fees	1,510	1,870
Warranty	1,160	1,081
Accrued capital expenditures		250
Other	2,324	2,587
Accrued expenses	$ 46,099	$ 46,147

Stock-Based Compensation Recogn

Stock-Based Compensation Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 15,934	$ 9,282	$ 28,179	$ 17,938
Cost of product revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	774	372	1,349	731
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	2,618	1,205	4,584	2,544
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 12,542	$ 7,705	$ 22,246	$ 14,663

Summary of Stock Option Activit

Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018
Options
Outstanding at beginning of period	1,282
Granted	76
Exercised	(425)
Cancelled and expired	(15)
Outstanding at end of period	918	1,282
Exercisable at end of period	669
Options vested and expected to vest at end of period	905
Weighted Average Exercise Price
Outstanding at beginning of period	$ 46.18
Granted	383.96
Exercised	24.95
Cancelled and expired	153.17
Outstanding at end of period	83.05	$ 46.18
Exercisable at end of period	38.86
Options vested and expected to vest at end of period	$ 82.85
Weighted Average Remaining Contractual Term (years)
Outstanding	5 years 11 months 19 days	5 years 3 months 21 days
Exercisable at end of period	4 years 11 months 19 days
Options vested and expected to vest at end of period	5 years 11 months 8 days
Aggregate Intrinsic Value
Outstanding at end of period	$ 331,490
Exercisable at end of period	271,255
Options vested and expected to vest at end of period	$ 327,147

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	6 Months Ended
	May 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Aggregate intrinsic value of options exercised in period		$ 155,400
Proceeds from the exercise of stock options		10,613	$ 5,257
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 15,800
Unrecognized stock-based compensation expense, estimated weighted-average recognition period		2 years 3 months 18 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Unrecognized stock-based compensation expense		$ 72,100
Unrecognized stock-based compensation expense, estimated weighted-average recognition period		2 years 3 months 18 days
Weighted average grant-date fair value		$ 379.63
Fair value of units vested		$ 163,300
Restricted share unit issued		192,000
Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share unit issued	114,000

Summary of Weighted Average Gra

Summary of Weighted Average Grant-Date Fair Values And Weighted Average Assumptions Used to Calculate Fair Value of Options Granted (Detail) - Stock Options - $ / shares	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value	$ 148.51	$ 57.38	$ 142.81	$ 50.26
Valuation assumptions:
Risk-free interest rate	2.87%	1.88%	2.93%	1.85%
Expected option life (years)	3 years 11 months 26 days	4 years 21 days	4 years 14 days	4 years 25 days
Expected volatility	43.90%	43.40%	42.70%	43.60%

Summary of Restricted Stock Uni

Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units shares in Thousands	6 Months Ended
	Sep. 30, 2018$ / sharesshares
Number of Shares
Beginning Balance | shares	880
Granted | shares	192
Vested | shares	(404)
Forfeited | shares	(20)
Ending Balance | shares	649
Weighted Average Grant Date Fair Value
Beginning Balance | $ / shares	$ 109.01
Granted | $ / shares	379.63
Vested | $ / shares	103.91
Forfeited | $ / shares	187.41
Ending Balance | $ / shares	$ 189.87

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	Dec. 22, 2017	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
U.S. federal statutory corporate tax rate		35.00%	21.00%	35.00%	21.00%	35.00%
Income tax provision (benefit)			$ 1,706,000	$ 7,981,000	$ (39,873,000)	$ 4,399,000
Effective income tax rate			3.30%	24.60%	(39.70%)	6.60%
Measurement period	1 year
Income tax expense			$ 0		$ 0
Excess tax benefits from stock-based awards			$ 12,900,000	$ 4,500,000	$ 66,800,000	$ 21,300,000
Potential repatriation of foreign subsidiary earnings					100.00%

Differences Between Statutory I

Differences Between Statutory Income Tax Rate and Effective Income Tax Rate (Detail)	1 Months Ended	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Statutory income tax rate	35.00%	21.00%	35.00%	21.00%	35.00%
Excess tax benefits from stock-based awards		(24.90%)	(13.70%)	(66.60%)	(32.10%)
Credits		(1.80%)	(1.20%)	(1.80%)	(1.20%)
State taxes, net		4.30%	3.50%	4.30%	3.50%
Permanent differences		1.80%	1.80%	1.80%	1.80%
Other		2.90%	(0.80%)	1.60%	(0.40%)
Effective tax rate		3.30%	24.60%	(39.70%)	6.60%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Oct. 01, 2018ft²	Dec. 31, 2017ft²	Jul. 31, 2018ft²	Feb. 28, 2017ft²	Oct. 31, 2016USD ($)	Sep. 30, 2016USD ($)	May 31, 2016	Sep. 30, 2015Patent	Sep. 30, 2018USD ($)	Mar. 31, 2018ft²
Magnetic Clutch Patents
Commitments and Contingencies [Line Items]
Patents allegedly infringed upon, number | Patent								2
European Pigtail Patent
Commitments and Contingencies [Line Items]
Patents allegedly infringed upon, number | Patent								1
German Pigtail Patent
Commitments and Contingencies [Line Items]
Patents allegedly infringed upon, number | Patent								1
Patent One
Commitments and Contingencies [Line Items]
Patent expiration period							2020-09
Patent Two
Commitments and Contingencies [Line Items]
Patent expiration period							2020-12
Patent Three
Commitments and Contingencies [Line Items]
Patent expiration period							2021-10
Lease Agreements | Massachusetts
Commitments and Contingencies [Line Items]
Annual rent expense | $									$ 0.9
Lease expiration date		Aug. 31, 2025	Sep. 30, 2027	Jul. 31, 2022
Additional office space | ft²		6,607	23,864	21,603						11,269
Lease Agreements | Germany
Commitments and Contingencies [Line Items]
Annual rent expense | $						$ 0.3
Lease commencement period						2017-05
Lease expiration period						2024-05
Lease Agreements | Japan
Commitments and Contingencies [Line Items]
Annual rent expense | $					$ 0.9
Lease expiration period					2021-09
Lease Agreements | Subsequent Event | Massachusetts
Commitments and Contingencies [Line Items]
Total office space | ft²	63,343

Segment and Enterprise Wide D_2

Segment and Enterprise Wide Disclosures - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017	Sep. 30, 2018USD ($)Segment	Sep. 30, 2017	Mar. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of business segments | Segment			1
International
Segment Reporting Information [Line Items]
Long-lived assets | $	$ 39.4		$ 39.4		$ 35.5
Customer Concentration Risk | Total Revenues | International
Segment Reporting Information [Line Items]
Percentage of revenue accounted	13.00%	11.00%	13.00%	10.00%