Deferred compensation (Stock-based Compensation Cost) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Share-based Compensation [Abstract]
Stock-based compensation cost	$ 1,260	$ 2,335	$ 2,720	$ 7,915
Less: stock-based compensation cost capitalized	(399)	(664)	(1,025)	(1,621)
Stock-based compensation expense	$ 861	$ 1,671	$ 1,695	$ 6,294
Number of vested shares repurchased	126,231	192,976	206,653	256,895
Payments for stock-based compensation	$ 708	$ 3,449	$ 1,171	$ 4,872
Estimated fair value per share at end of period (in dollars per share)	$ 4.71		$ 4.71
Aggregate intrinsic value of unvested restricted shares outstanding	$ 3,711		$ 3,711
Deferred compensation current	43		43		$ 17
Unrecognized stock-based compensation cost	$ 4,455		$ 4,455
Weighted-average period for unrecognized compensation cost to be recognized			1 year 2 months 3 days

Allocated share based compensation expense benefit.

No definition available.

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- Definition

Employee service share based compensation allocation of recognized period income (costs) capitalized amount.

+ References

No definition available.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable within one year (or the operating cycle, if longer). Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

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- Definition

Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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- Definition

Per share weighted average intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options.

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- Definition

Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

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- Definition

Intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options.

+ References

No definition available.

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- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

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