Sale of SEI Asset Korea (Narrative) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013	Mar. 28, 2013 SEI Asset Korea Co., Ltd. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of subsidiary	$ 5,582	$ 22,112
Gain on sale of subsidiary, diluted earnings per share impact, net	$ 0.02	$ 0.08
Contingent purchase price from sale of SEI AK			11,220
Revenues and Net Income Included on Company's Consolidated Statement of Operations
Revenues			2,889
Net income			796
Less: Income attributable to the noncontrolling interests			350
Net income attributable to SEI AK			$ 446

Disposal Group, Proceeds From Sale Contingent Purchase Amount

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Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of gain (loss) on sale or disposal of equity in securities of subsidiaries.

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Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items, which is apportioned to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This item includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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The amount of net income (loss) for the period attributable to extraordinary items that is available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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