Shareholder's Equity - Schedule of Aggregate Intrinsic Value of Stock Options Exercised, Fair Values of Awards Vested, and Share Based Liabilities Settled (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total intrinsic value of stock options exercised	$ 1,619	$ 403	$ (36)
Total grant-date fair value of stock options vested	1,317	1,384	1,168
Total share-based liabilities settled	0	76	16,858
Restricted Shares (RSAs and RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total grant-date fair value of restricted shares vested	447	614	18,284
Total settlement date fair value of restricted shares vested	$ 1,074	$ 1,236	$ 21,134