Stock-Based Compensation (Details) - USD ($) $ in Thousands			3 Months Ended		12 Months Ended
	Apr. 02, 2018	Jan. 17, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018	Dec. 31, 2017	Jul. 12, 2017	Dec. 31, 2016
Stock-Based Compensation
Share-based compensation expense			$ 959	$ 310
Common stock, shares authorized							1,600,000,000	1,600,000,000	1,600,000,000
Common stock, shares issued							152,565,218	150,578,451
2018 Plan
Stock-Based Compensation
Restricted stock units outstanding							24,535
Unvested RSUs			5,400	8,887	8,887	8,887	5,400	5,400		8,887
Maximum percentage of fair market value per share granted		100.00%
Expiration of stock options		10 years
Common stock, shares authorized		8,323,764
Common stock, shares issued							0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Balance at the beginning of the period			5,400	8,887	8,887
Shares forfeited (in shares)					(1,192)
Shares vested (in shares)					(2,295)
Balance at the end of the period			5,400		5,400	8,887
Weighted Remaining Contractual Life (Years)			1 year 29 days		1 year 3 months 29 days	2 years 4 days
Aggregate Intrinsic Value							$ 1,573	$ 1,633		$ 1,567
Unrecognized compensation expense							$ 5,000
Unrecognized compensation expense, recognition period			1 year 29 days
Restricted stock units (RSUs) | 2013 Long Term Incentive Plan
Stock-Based Compensation
Restricted stock units outstanding							24,535
Unvested RSUs									9,880
Share-based compensation expense			$ 900
Restricted stock units (RSUs) | 2013 Long Term Incentive Plan | Minimum
Stock-Based Compensation
Vesting period of remaining RSU's which will vest by 2019			3 years
Restricted stock units (RSUs) | 2013 Long Term Incentive Plan | Maximum
Stock-Based Compensation
Vesting period of remaining RSU's which will vest by 2019			4 years
Restricted stock units (RSUs) | 2018 Plan | Directors
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Shares granted (in shares)	201,720
Grant date fair value of units issued	$ 1,100
Restricted stock units (RSUs) | 2018 Plan | Directors | First issued shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Shares granted (in shares)	86,874
Restricted stock units (RSUs) | 2018 Plan | Directors | Second issued shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Shares granted (in shares)	120,146
Restricted stock units (RSUs) | 2018 Plan | Directors | Vesting percentage, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Vesting percentage	33.33%
Restricted stock units (RSUs) | 2018 Plan | Directors | Vesting percentage, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Vesting percentage	33.33%
Restricted stock units (RSUs) | 2018 Plan | Directors | Vesting percentage, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Vesting percentage	33.33%