Subsequent Events - Class B to Class A Share Exchanges (Details) $ in Millions		9 Months Ended	12 Months Ended
	Oct. 02, 2017 USD ($) shares	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Subsequent Events
TRA liability		$ 55.8	$ 43.0
Increase in TRA liability		$ (4.9)	$ (2.7)
Subsequent events
Subsequent Events
Shares exchange ratio	1
Increase in TRA liability	$ 50.3
Class A common stock | Subsequent events
Subsequent Events
Exchange of Class B shares for Class A shares (in shares) | shares	12,689,815