Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These condensed consolidated financial statements are unaudited and, in the opinion of management, include all adjustments necessary for a fair statement of the financial position and results of operations of the Company for the interim periods presented. Such adjustments consisted only of normal recurring items. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). In accordance with GAAP for interim financial reports and the instructions for Form 10-Q and the rules of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual financial statements have been condensed or omitted. Our accounting policies are described in the Notes to the Consolidated Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2017 (our “Annual Report”). Interim results are not necessarily indicative of the results of operations for the full year. These interim financial statements should be read in conjunction with our Annual Report.
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include our accounts and the accounts of our wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the related disclosure of contingent assets and liabilities. The most significant estimates and assumptions are used to determine amounts and values of, but are not limited to: revenue recognition related to product sales and services revenue; product sales allowances and accruals; allowance for doubtful accounts; marketable securities; inventory; acquisition date fair value and subsequent fair value estimates used to assess impairment of long-lived assets, including goodwill, in-process research and development (“IPR&D”) and other intangible assets; contingent consideration; debt obligations; certain accrued liabilities, including clinical trial accruals; income taxes, inclusive of valuation allowances; and equity-based compensation expense. Actual results could differ materially from those estimates.
Restricted Cash	Restricted Cash As of March 31, 2018 and December 31, 2017, we classified $0.7 million of our cash as restricted cash, a non-current asset on the balance sheet. This amount represented the security deposit delivered to the landlord of our Waltham, Massachusetts headquarters in the form of an irrevocable letter of credit.
Concentrations and Significant Customer Information	Our net accounts receivable primarily represent amounts due for products sold directly to wholesalers, distributors, and specialty pharmacies and amounts due for CBR Services sold to consumers who pay for the services directly. Accounts receivable for our products and services are recorded net of reserves for estimated chargeback obligations, prompt payment discounts and any allowance for doubtful accounts. Concentrations and Significant Customer Information Financial instruments which potentially subject us to concentrations of credit risk consist principally of cash and cash equivalents, marketable securities, and accounts receivable. We currently hold our excess cash primarily in institutional money market funds, corporate debt securities, U.S. treasury and government agency securities, commercial paper and certificates of deposit. We are currently dependent on a single supplier for Feraheme drug substance (produced in two separate facilities) and finished drug product as well as for drug substance and final packaging services for Intrarosa. In addition, we rely on single sources for certain materials required to support the CBR Services. We would be exposed to a significant loss of revenue from the sale of our products and services if our suppliers and/or manufacturers could not fulfill demand for any reason. Our operations are located entirely within the U.S. We focus primarily on developing, manufacturing, and commercializing our products and product candidates and marketing and selling the CBR Services. We perform ongoing credit evaluations of our product sales customers and generally do not require collateral.
Recently Issued and Adopted Accounting Pronouncements	On January 1, 2018, we adopted ASC 606 applying the modified retrospective transition method to all contracts that were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for prior periods. We recorded a net increase to opening stockholders' equity of $1.1 million as of January 1, 2018, reflecting the cumulative impact of adopting ASC 606 primarily related to the capitalization of incremental direct costs of obtaining a contract, which consisted of sales commissions related to the CBR Services. There was no impact to revenue for the three months ended March 31, 2018. RECENTLY ISSUED AND PROPOSED ACCOUNTING PRONOUNCEMENTS From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by us as of the specified effective date. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This standard requires entities to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. ASU 2016-13 will be effective for us for fiscal years beginning on or after January 1, 2020, including interim periods within those annual reporting periods and early adoption is permitted. We are currently evaluating the impact of our adoption of ASU 2016-13 on our condensed consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”). This statement requires entities to recognize on its balance sheet assets and liabilities associated with the rights and obligations created by leases with terms greater than twelve months. This statement is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those annual periods and early adoption is permitted. We have formed a project team to assess the impact of adopting ASU 2016-02 on our condensed consolidated financial statements. We currently expect that most of our operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon our adoption of ASU 2016-02. RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”), which requires amounts generally described as restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling beginning-of-period and end-of-period total amounts shown on the statement of cash flows. We adopted the standard on January 1, 2018 using the retrospective approach and modified the presentation of our condensed condensed statements of cash flows in accordance with the standard. The adoption of ASU 2016-18 did not have a material impact on our condensed consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). This standard clarifies certain aspects of the statement of cash flows, including the classification of debt prepayment or debt extinguishment costs or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate owned life insurance policies, distributions received from equity method investees and beneficial interests in securitization transactions. This new standard also clarifies that an entity should determine each separately identifiable source of use within the cash receipts and payments on the basis of the nature of the underlying cash flows. In situations in which cash receipts and payments have aspects of more than one class of cash flows and cannot be separated by source or use, the appropriate classification should depend on the activity that is likely to be the predominant source or use of cash flows for the item. We adopted the standard on January 1, 2018 using the retrospective approach. The adoption of ASU 2016-15 did not have a material impact on our condensed consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”).This new standard amends certain aspects of accounting and disclosure requirements of financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in our results of operations. This new standard does not apply to investments accounted for under the equity method of accounting or those that result in consolidation of the investee. Equity investments that do not have readily determinable fair values may be measured at fair value or at cost minus impairment adjusted for changes in observable prices. A financial liability that is measured at fair value in accordance with the fair value option is required to be presented separately in other comprehensive income for the portion of the total change in the fair value resulting from change in the instrument-specific credit risk. In addition, a valuation allowance should be evaluated on deferred tax assets related to available-for-sale debt securities in combination with other deferred tax assets. We adopted the standard on January 1, 2018 using the modified retrospective approach. The adoption of ASU 2016-01 did not have a material impact on our condensed consolidated financial statements.
Revenue Recognition	Performance Obligations At contract inception, we assess the goods and services promised in our contracts with customers and identify a performance obligation for each promise to transfer to the customer a good or service (or bundle of goods or services) that is distinct. To identify the performance obligations, we consider all of the goods or services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. We determined that the following distinct goods and services represent separate performance obligations: •Supply of Makena product •Supply of Feraheme product •Supply of Intrarosa product •CBR collection and processing services •CBR storage services Product Revenue For performance obligations related to products (i.e. Makena, Feraheme and Intrarosa), we principally sell our products to wholesalers, specialty distributors, specialty pharmacies and other customers (collectively, “Customers”), who purchase products directly from us. Our Customers subsequently resell the products to healthcare providers and patients. In addition to distribution agreements with Customers, we enter into arrangements with healthcare providers and payers that provide for government-mandated and/or privately-negotiated rebates, chargebacks and discounts with respect to the purchase of our products. For the majority of our Customers, we transfer control at the point in time when the goods are delivered. In instances when we perform shipping and handling activities, these are considered fulfillment activities, and accordingly, the costs are accrued when the related revenue is recognized. Taxes collected from Customers and remitted to governmental authorities are excluded from revenues. Variable Consideration Under ASC 606, we are required to make estimates of the net sales price, including estimates of variable consideration (such as rebates, chargebacks, discounts, co-pay assistance and other deductions), and recognize the estimated amount as revenue, when we transfer control of the product to our customers. Variable consideration must be determined using either an “expected value” or a “most likely amount” method. We record product revenues net of certain allowances and accruals in our condensed consolidated statements of operations. Product sales allowances and accruals are primarily comprised of both direct and indirect fees, discounts and rebates and provisions for estimated product returns. Direct fees, discounts and rebates are contractual fees and price adjustments payable to Customers that purchase products directly from us. Indirect fees, discounts and rebates are contractual price adjustments payable to healthcare providers and organizations, such as certain physicians, clinics, hospitals, group purchasing organizations (“GPOs”), and dialysis organizations that typically do not purchase products directly from us but rather from wholesalers and specialty distributors. Consideration payable to a Customer, or other parties that purchase goods from the Customer, are considered to be a reduction of the transaction price, and therefore, of revenue. Product sales allowances and accruals are based on definitive contractual agreements or legal requirements (such as Medicaid laws and regulations) related to the purchase and/or utilization of the product by these entities and are recorded in the same period that the related revenue is recognized. We use the expected value method for estimating variable consideration. We estimate product sales allowances and accruals using either historical, actual and/or other data, including estimated patient usage, applicable contractual rebate rates, contract performance by the benefit providers, other current contractual and statutory requirements, historical market data based upon experience of our products and other products similar to them, specific known market events and trends such as competitive pricing and new product introductions, current and forecasted Customer buying patterns and inventory levels, and the shelf life of our products. As part of this evaluation, we also review changes to federal and other legislation, changes to rebate contracts, changes in the level of discounts, and changes in product sales trends. Although allowances and accruals are recorded at the time of product sale, rebates are typically paid out in arrears, one to three months after the sale. The estimate of variable consideration, which is included in the transaction price, may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved in a future period. Estimating variable consideration and the related constraint requires the use of significant management judgment and actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. No amounts were constrained as of March 31, 2018. Discounts We typically offer a 2% prompt payment discount to certain customers as an incentive to remit payment in accordance with the stated terms of the invoice, generally 30 days. Because we anticipate that those customers who are offered this discount will take advantage of the discount, 100% of the prompt payment discount at the time of sale are accrued, based on the gross amount of each invoice. We adjust the accrual quarterly to reflect actual experience. Chargebacks Chargeback reserves represent the estimated obligations resulting from the difference between the prices at which we sell our products to wholesalers and the sales price ultimately paid to wholesalers under fixed price contracts by third-party payers, including governmental agencies. The chargeback estimates are determined based on actual product sales data and forecasted customer buying patterns. Actual chargeback amounts are determined at the time of resale to the qualified healthcare provider, and we generally issue credits for such amounts within several weeks of receiving notification from the wholesaler. Estimated chargeback amounts are recorded at the time of sale and adjusted quarterly to reflect actual experience. Distributor/Wholesaler and Group Purchasing Organization Fees Fees under the arrangements with distributors and wholesalers are usually based upon units of product purchased during the prior month or quarter and are usually paid by us within several weeks of the receipt of an invoice from the wholesaler or distributor, as the case may be. Fees under the arrangements with GPOs are usually based upon member purchases during the prior quarter and are generally billed by the GPO within 30 days after period end. In accordance with ASC 606, since the consideration given to the Customer is not for a distinct good or service, the consideration is a reduction of the transaction price of the vendor’s products or services. We have included these fees in contractual adjustments in the table above. We generally pay such amounts within several weeks of the receipt of an invoice from the distributor, wholesaler or GPO. Accordingly, we accrue the estimated fee due at the time of sale, based on the contracted price invoiced to the Customer. We adjust the accrual quarterly to reflect actual experience. Product Returns Consistent with industry practice, we generally offer wholesalers, specialty distributors and other customers a limited right to return our products based on the product’s expiration date. Currently the expiration dates for Feraheme, Makena and Intrarosa have a range of three to five years. Product returns are estimated based on the historical return patterns and known or expected changes in the marketplace. We track actual returns by individual production lots. Returns on lots eligible for credits under our returned goods policy are monitored and compared with historical return trends and rates. We expect that wholesalers and healthcare providers will not stock significant inventory due to the cost of the product, the expense to store our products, and/or that our products are readily available for distribution. We record an estimate of returns at the time of sale. If necessary, our estimated rate of returns may be adjusted for actual return experience as it becomes available and for known or expected changes in the marketplace. We did not significantly adjust our reserve for product returns during the three months ended March 31, 2018. To date, our product returns have been relatively limited; however, returns experience may change over time. We may be required to make future adjustments to our product returns estimate, which would result in a corresponding change to our net product sales in the period of adjustment and could be significant. Sales Rebates We contract with various private payer organizations, primarily pharmacy benefit managers, for the payment of rebates with respect to utilization of our products. We determine our estimates for rebates, if applicable, based on actual product sales data and our historical product claims experience. Rebate amounts generally are invoiced quarterly and are paid in arrears, and we expect to pay such amounts within several weeks of notification by the provider. We regularly assess our reserve balance and the rate at which we accrue for claims against product sales. If we determine in future periods that our actual rebate experience is not indicative of expected claims, if actual claims experience changes, or if other factors affect estimated claims rates, we may be required to adjust our current accumulated reserve estimate, which would affect net product sales in the period of the adjustment and could be significant. Governmental Rebates Governmental rebate reserves relate to our reimbursement arrangements with state Medicaid programs. We determine our estimates for Medicaid rebates, if applicable, based on actual product sales data and our historical product claims experience. In estimating these reserves, we provide for a Medicaid rebate associated with both those expected instances where Medicaid will act as the primary insurer as well as in those instances where we expect Medicaid will act as the secondary insurer. Rebate amounts generally are invoiced quarterly and are paid in arrears, and we expect to pay such amounts within several weeks of notification by the Medicaid or provider entity. We regularly assess our Medicaid reserve balance and the rate at which we accrue for claims against product sales. If we determine in future periods that our actual rebate experience is not indicative of expected claims, if actual claims experience changes, or if other factors affect estimated claims rates, we may be required to adjust our current Medicaid accumulated reserve estimate, which would affect net product sales in the period of the adjustment and could be significant. Other Incentives Other incentives which we offer include voluntary patient assistance programs, such as co-pay assistance programs, which are intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payers. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that we expect to receive associated with product that has been recognized as revenue. Service Revenue The CBR Services include the collection, processing, and storage of both umbilical cord blood and cord tissue. We market and sell the CBR Services directly to consumers at the prices that are known at contract inception. The discounts offered to the customer are known at the time of enrollment and thereby do not result in variable consideration. CBR Services include the following two performance obligations: collection and processing and storage services, further described below. Collection and Processing Services Enrollment services, including the provision of a collection kit and cord blood and cord tissue unit processing, are delivered at the beginning of the relationship. The revenue for this performance obligation is recognized at the point in time after the collection and successful processing of the cord blood and cord tissue. When purchasing collection and processing services, the customer can (a) pay for the service upfront, when the service is provided; (b) finance the processing fee with us over six or twelve months; or (c) finance the processing fee through a third-party provider, and therefore not finance the arrangement with us. We elected to apply the practical expedient and therefore we have not adjusted the promised consideration for the effects of financing for either the six or twelve month payment plans. Storage Services Payment options for storage services of newborn cord blood and cord tissue units include either (a) an annual fee or (b) a prepayment of 18 years or for the lifetime of the newborn donor (the “lifetime option”). The revenue for this performance obligation is recognized ratably over the storage period on a straight-line basis, which is consistent with how the services are provided. For the lifetime option, storage fees are not charged during the lifetime of the newborn donor. However, revenue is recognized based on the average of male and female life expectancies using lifetime actuarial tables published by the Social Security Administration in effect at the time of the newborn’s birth. We determined that the 18 year and lifetime prepayment options do not include a significant financing component as the payment terms were structured primarily for reasons other than for the provision of financing and to maximize profitability. Under ASC 606, we recognize revenue when our customer obtains control of promised goods or services in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. To determine revenue recognition for arrangements that we determine are within the scope of ASC 606, we perform the following five steps: a.Identify the contract(s) with a customer; b.Identify the performance obligations in the contract; c.Determine the transaction price; d.Allocate the transaction price to the performance obligations in the contract; and e.Recognize revenue when (or as) the performance obligations are satisfied. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. At contract inception, if the contract is determined to be within the scope of ASC 606, we assess the goods or services promised within each contract, determine those that are performance obligations, and assess whether each promised good or service is distinct. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. We receive payments from customers based upon contractual billing schedules; accounts receivable are recorded when the right to consideration becomes unconditional. Contract assets include deferred contract acquisition costs, which will be amortized along with the associated revenue. Contract liabilities include payments received in advance of performance under the contract, and are realized with the associated revenue recognized under the contract. Allocation of Transaction Price We have selected an adjusted market assessment approach to estimate the stand-alone selling prices of the collection and processing services and storage services and concluded that the published list price is the price that a customer in that market would be willing to pay for those goods or services. We also considered the fact that all customers are charged the list prices current at the time of their enrollment where we have separately stated list prices for processing and storage. The discounts provided to the customers at the time of entering into the contract are allocated proportionally to both performance obligations (i.e. processing and storage). Cost to Obtain a Contract We pay commissions to internal sales representatives as compensation for obtaining contract enrollments for the CBR Services. We capitalize commissions that are incremental as a result of obtaining customer contracts and costs incurred to fulfill a customer contract if those costs are not within the scope of another topic within the accounting literature and meet the specified criteria. These costs are deferred in other current or long-term assets and are expensed to selling, general and administrative expenses as we satisfy the performance obligations by transferring the service to the customer. These assets will be periodically assessed for impairment.