Stock-Based Compensation - Restricted Stock Awards - Narrative (Details) - Restricted Stock Awards - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 2.5	$ 1.4
Fair value of restricted stock vested	2.6	0.7
Unrecognized compensation expense	$ 1.7	$ 4.6
Weighted-average period the unrecognized compensation cost is expected to be recognized	2 years

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 to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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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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