Share-Based Compensation - Summary of Grant Date Fair Value of Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options	$ 3,699	$ 6,102	$ 3,685
Restricted stock	4,217	3,147	2,985
Total	$ 7,916	$ 9,249	$ 6,670