Stock Based Compensation - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation cost not yet recognized	$ 17.3		$ 17.3
Compensation cost not yet recognized, period of recognition			3 years 10 months 12 days
Options granted in period (in shares)	1,278,000	220,875	1,278,000	784,375