Equity-Based Compensation (Aggregate Intrinsic Value of Options Exercised and Aggregate Fair Value of Restricted Stock Units and Restricted Shares that Vested) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options exercised	$ 3,812	$ 1,371	$ 2,128
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	11,851	10,017	5,307
Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	190	285	149
Deferred Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	$ 570	$ 285	$ 369

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

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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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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