Stock-Based Compensation - Plan Information (Details) - 2012 Plan - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Stock based compensation
Number of awards approved for grant (in shares)	4,000,000
Common stock remaining available for issuance (in shares)	17,229
Compensation expense	$ 3.8	$ 2.5
Board of Directors
Stock based compensation
Common shares granted to members of board of directors as compensation for director services	10,291	7,958

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

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