Equity-Based Incentive Plans (Restricted Stock Units) (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of RSUs
Outstanding	1,557,994	1,348,066	1,413,642
Granted	1,017,518	1,038,812	815,761
Vested	(811,317)	(769,291)	(817,226)
Forfeited	(65,616)	(59,593)	(64,111)
Outstanding	1,698,579	1,557,994	1,348,066
Weighted Average Grant Date Fair Value
Outstanding	$ 32.53	$ 36.32	$ 34.22
Granted	33.54	29.87	36.70
Vested	36.09	35.32	33.20
Forfeited	32.20	36.03	34.51
Outstanding	$ 31.44	$ 32.53	$ 36.32
Aggregate Intrinsic Value
Outstanding	$ 62,627	$ 53,034	$ 40,496	$ 60,970
Unrecognized Compensation
Outstanding	$ 35,821	33,581	31,996	$ 32,017
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Weighted average remaining life	1 year 4 months 28 days
Fair value of instruments vested during the period	$ 29,900	$ 26,200	$ 24,500
Total shares withheld	266,000	250,000	268,000

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

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Intrinsic value of outstanding award under share-based payment arrangement. Excludes share and unit options.

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Number of shares used to settle grantee's tax withholding obligation for award under share-based payment arrangement.

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