Amount of liability recognized arising from contingent consideration in a business combination.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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 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 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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Share-Based Payments OP Units (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jul. 18, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Contingent Consideration, Liability	$ 110,600
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 33.39
OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		2,872,252	2,999,987
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(127,735)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 33.39	$ 33.39
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 4,300	$ 3,200	$ 7,200
JBG Companies [Member]
Business Combination, Contingent Consideration, Liability	$ 110,591
JBG Companies [Member] \| OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	3,300,000
Minimum [Member] \| OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	12 months
Maximum \| OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	60 months
Measurement Input, Price Volatility [Member] \| OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum	18.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	27.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum	1.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum	1.50%
Measurement Input, Expected Term [Member] \| Minimum [Member] \| OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	1 year
Measurement Input, Expected Term [Member] \| Maximum \| OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	3 years