Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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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 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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Stock-Based Compensation - Performance Based Equity Awards (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended			6 Months Ended
	May 04, 2020	Aug. 06, 2018	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Stock-Based Compensation
Stock- based stock awards expense			$ 7,173		$ 6,906	$ 14,310	$ 13,758
Performance-Based Equity Awards
Stock-Based Compensation
Granted (in shares)		50,000		5,000
Weighted average grant-date fair value (in dollars per share)		$ 61.85
Stock- based stock awards expense					$ 399		$ 1,314
Unrecognized compensation expense (in dollars)								$ 0
Performance-Based Equity Awards \| Employee
Stock-Based Compensation
Granted (in shares)	10,686
Weighted average grant-date fair value (in dollars per share)	$ 56.14
Stock- based stock awards expense			0			0
Unrecognized compensation expense (in dollars)			$ 600			$ 600