Share Incentive and Other Compensation - Employee 401 (k) Plan (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employer matching contribution (in percent)	50.00%
Maximum annual contribution per employee (in percent)	6.00%
Maximum employee annual salary contribution (in percent)	15.00%
Maximum employee annual salary contribution amount	$ 18