Share-Based Compensation Arrangement By Share-Based Payment Award, Award Waiting Period

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Market Paid Price Offering Date

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Share-Based Payment Arrangement, Expense, Increase (Decrease)

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Stock Repurchase Program, Additional Authorized Amount

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

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- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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.

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Number of shares authorized for issuance under share-based payment arrangement.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Price of a single share of a number of saleable stocks of a company.

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Percentage of vesting of award under share-based payment arrangement.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Number of non-vested options outstanding.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Amount remaining of a stock repurchase plan authorized.

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Shareholders' Equity (Narrative) (Details) - USD ($)			12 Months Ended
Shareholders' Equity (Narrative) (Details) - USD ($)	Jun. 02, 2021	Dec. 08, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 10, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of stock options granted (in USD per share)			$ 14.94	$ 13.53	$ 13.94
Increase (decrease) in stock-based compensation from change in management's estimate			$ 5,880,000	$ (2,659,000)	$ 2,903,000
Unvested employee stock options outstanding (in shares)			10,446,000
Unrecognized compensation cost from employee stock options			$ 104,770,000
Weighted average period for recognition of unrecognized compensation cost			1 year 10 months 24 days
Total options that were exercisable (in shares)			8,638,000	6,641,000
Options outstanding weighted average remaining contractual life, years			6 years 9 months 18 days
Total intrinsic value of options exercised			$ 55,029,000	$ 46,426,000
Aggregate intrinsic value of options exercisable			117,496,000
Total intrinsic value of options outstanding			$ 149,989,000
Share price of SEI common stock (in USD per share)			$ 60.94
Dividends declared per common share (in USD per share)	$ 0.37	$ 0.40	$ 0.77	$ 0.72	$ 0.68
Dividends declared			$ 107,840,000	$ 104,588,000	$ 102,435,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award waiting period			2 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award waiting period			4 years
Common Stock Buyback
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in the stock repurchase program						$ 200,000,000
Remaining stock repurchase authorization amount			$ 231,293,000
2014 Equity Compensation Plan \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate			50.00%
2014 Equity Compensation Plan \| Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate			50.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan, employee eligible percentage on offerings of common stock			85.00%
Shares reserved under the plan			15,652,000
Issuance of common stock under the employee stock purchase plan, shares			12,307,000
Employee stock purchase plan			$ 0	$ 0	$ 0