Stock-based Compensation - Summary of Stock-based Compensation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 934	$ 482	$ 1,755	$ 969
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	680	130	1,060	295
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	249	323	682	604
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 5	$ 29	$ 13	$ 70