v3.8.0.1

Defined Contribution Plan - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Defined Contribution Plan Disclosure [Line Items] |  |  |
Contribution expense | $ 0.7 | $ 0.3 | $ 0.3
U.S. [Member] | 401 (K) Retirement and Savings Plan [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Percentage of employee contributions | 50.00% |  |
Percentage of employee eligible compensation | 6.00% |  |
Ireland [Member] | Defined Contribution PRSA Plan [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Percentage of employee contributions | 8.00% |  |
Percentage of employee eligible compensation | 6.00% |  |

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_RetirementPlanSponsorLocationAxis=us-gaap_DomesticPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RetirementPlanNameAxis=srdx_FourZeroOneKRetirementAndSavingsPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RetirementPlanSponsorLocationAxis=us-gaap_ForeignPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RetirementPlanNameAxis=srdx_DefinedContributionPersonalRetirementSavingsAccountPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |