Stock-based Compensation - Narrative (Details) - 2015 Omnibus Incentive Plan - Restricted Stock Units (RSUs) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in period (in shares)		70,000	70,000	111,281	390,352
Shares granted in period			$ 404	$ 909	$ 4,100
Share-based compensation expense	$ 719	$ 716
Share-based compensation expense not yet recognized	$ 1,500

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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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).

+ References

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