Stock-Based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Employee
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 4,617
Post-Tax	747	$ 386
Pre-Tax	946	488
Director
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	602
Post-Tax	499	443
Pre-Tax	$ 632	$ 561

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
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