Stock-based Compensation - Equity Compensation expense for RSUs and RSAs with Financial or other Performance based vesting requirments (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted		143,283
June 2014 Grant Date [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted		143,283
Employee Service Share Based Compensation Nonvested Awards Compensation Cost Recognized Share Based Awards Other than Options		$ 132
Fair Value of Performance Awards on Grant Date		721
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		$ 589
Latest Date that Performance condition could be met		December 2017
Scenario, Forecast [Member]
Awards expected to expire	114,379