Stock Based Compensation - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation cost not yet recognized	$ 16.3		$ 16.3
Compensation cost not yet recognized, period of recognition			3 years 7 months 28 days
Options granted in period (in shares)	20,000	21,000	1,300,000	805,375