Income Taxes (Tax Effect Of Significant Temporary Differences Representing Deferred Tax Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Tax Liabilities, Net [Abstract]
Difference in financial reporting and income tax depreciation methods	$ (3,637)	$ (7,043)
Reserves not currently deductible	209	235
Capitalized software currently deductible for tax purposes, net of amortization	(118,841)	(119,800)
State deferred income taxes	(420)us-gaap_DeferredTaxAssetsStateTaxes	251us-gaap_DeferredTaxAssetsStateTaxes
Revenue and expense recognized in different periods for financial reporting and income tax purpose	6,212	3,856
Unrealized holding gain on investments	(475)	(308)
Stock-based compensation expense	(38,989)	(45,555)
State net operating loss carryforward	24,150	21,215
Valuation allowance on deferred tax assets	(16,509)	(14,738)
Federal benefit of state tax deduction for uncertain tax positions	2,913	2,643
Foreign tax credit	2,327us-gaap_DeferredTaxAssetsOther	0us-gaap_DeferredTaxAssetsOther
Foreign deferred including taxes on cumulative undistributed earnings of SEI AK	(87)	(91)
Net deferred income tax liability	$ (65,169)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ (68,225)us-gaap_DeferredTaxAssetsLiabilitiesNet

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from equity method investments.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from state taxes.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the allowance for doubtful accounts.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from contingent liabilities.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of deferred tax liability attributable to taxable temporary differences from capitalized software.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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Amount of deferred tax liability attributable to taxable temporary differences from undistributed earnings of subsidiaries and other recognized entities not within the country of domicile of the entity.

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Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains on trading securities.

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