XML 48 R35.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Expense related to soft dollar arrangement | $ 3,265 | $ 3,429 | $ 7,232 | $ 7,502 |
Cash and cash equivalents invested in SEI-sponsored money market funds | 693,442 |  | 693,442 |  | $ 744,247
Restricted cash | 3,509 |  | 3,509 |  | 3,505
Capitalized software development costs |  |  | 24,613 | $ 33,292 |
Net book value of capitalized software | $ 312,814 |  | $ 312,814 |  | 310,405
Anti-dilutive employee stock options | 6,221 | 11,255 | 6,138 | 11,267 |
Anti-dilutive employee stock options, per share | $ 53.33 | $ 37.68 | $ 53.03 | $ 37.69 |
SEI Wealth Platform |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Capitalized software development costs |  |  | $ 23,768 | $ 27,994 |
Net book value of capitalized software | $ 289,376 |  | 289,376 |  |
Capitalized software in progress | $ 36,189 |  | 36,189 |  |
Amortization expense of capitalized software |  |  | 19,599 | 24,486 |
SEI Wealth Platform | Weighted Average |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Estimated useful life of capitalized software | 8 years 4 months 24 days |  |  |  |
Application for Investment Managers segment [Member] |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Capitalized software development costs |  |  | 845 | $ 5,298 |
Net book value of capitalized software | $ 23,438 |  | 23,438 |  |
Estimated useful life of capitalized software | 5 years |  |  |  |
Amortization expense of capitalized software |  |  | 2,605 |  |
SEI Investments (Europe) Limited |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Restricted cash | $ 3,000 |  | 3,000 |  | 3,000
SEI Investments Distribution Co. (SIDCO) |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Restricted cash | 509 |  | 509 |  | 505
SEI-Sponsored Open-Ended Money Market Mutual Funds |  |  |  |  |
Summary of Significant Accounting Policies [Line Items] |  |  |  |  |
Cash and cash equivalents invested in SEI-sponsored money market funds | $ 314,718 |  | $ 314,718 |  | $ 401,292

X
- Definition Capitalized software development costs in progress associated with future releases. + References No definition available. + Details
Name: | seic_CapitalizedSoftwareDevelopmentCostsInProgress
Namespace Prefix: | seic_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Expense Related To Soft Dollar Arrangement + References No definition available. + Details
Name: | seic_ExpenseRelatedToSoftDollarArrangement
Namespace Prefix: | seic_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Summary of Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | seic_SummaryofSignificantAccountingPoliciesLineItems
Namespace Prefix: | seic_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic net Income or Loss per outstanding limited partnership unit in the future and that were not included in the computation of diluted net income per limited partnership unit, because to do so would increase net income per unit amounts or decrease loss per unit amounts for the period presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1536-109256 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1533-109256 + Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfNetIncomePerOutstandingUnitAmount
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Additions made to capitalized computer software costs during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
Name: | us-gaap_CapitalizedComputerSoftwareAdditions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expense for amortization of capitalized computer software costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756 + Details
Name: | us-gaap_CapitalizedComputerSoftwareAmortization1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756 + Details
Name: | us-gaap_CapitalizedComputerSoftwareNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3044-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3044-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=seic_SeiWealthPlatformMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=seic_PlatformfortheInvestmentManagerssegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis=seic_SeiInvestmentsEuropeLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis=seic_SeiInvestmentsDistributionCoSidcoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=seic_SeiSponsoredOpenEndedMoneyMarketMutualFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |