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Sale of SEI Asset Korea (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 28, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of subsidiary	$ 0	$ 2,791
SEI Asset Korea Co., Ltd. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent purchase price from sale of SEI AK			$ 11,220
Gain on sale of subsidiary		$ 2,791
Gain on sale of subsidiary, diluted earnings per share impact, net		$ 0.01

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
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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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-Publisher FASB
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