Common Stock (Details) $ in Thousands			1 Months Ended	3 Months Ended	6 Months Ended
	May 09, 2017 USD ($) class_of_stock shares	May 09, 2017 USD ($) class_of_stock shares	Jul. 31, 2018 shares	Jun. 30, 2018 USD ($) shares	Jun. 30, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Jun. 30, 2017 shares	May 08, 2017 shares
Bold Contribution Agreement
Capital Unit [Line Items]
Number of classes of common stock | class_of_stock	2	2
Member Units | Bold Contribution Agreement
Capital Unit [Line Items]
Stock conversion (in shares)					1
2014 Plan
Capital Unit [Line Items]
Common stock, shares issued (in shares)				255,313	255,313
Class A Common Stock
Capital Unit [Line Items]
Common stock, shares issued (in shares)				28,131,464	28,131,464	27,584,638
Common stock, shares outstanding (in shares)				28,131,464	28,131,464	27,584,638
Common stock issued, value | $				$ 28	$ 28	$ 28
Class A Common Stock | Bold Contribution Agreement
Capital Unit [Line Items]
Stock recapitalization ratio		1
Common stock, shares issued (in shares)	150,000	150,000
Common stock issued, value | $	$ 2,000	$ 2,000
Stock conversion (in shares)		1			1
Class A Common Stock | 2014 Plan
Capital Unit [Line Items]
Common stock, shares issued (in shares)				341,585	341,585		84,825	382,804
Class B Common Stock
Capital Unit [Line Items]
Common stock, shares issued (in shares)				35,846,928	35,846,928	36,052,169
Common stock, shares outstanding (in shares)				35,846,928	35,846,928	36,052,169
Common stock issued, value | $				$ 36	$ 36	$ 36
EEH Units and Class B Common Stock converted to Class A Common Stock (in shares)				11,195	205,241
Class B Common Stock | Bold Contribution Agreement
Capital Unit [Line Items]
Stock conversion (in shares)		1
Subsequent Event | Class B Common Stock
Capital Unit [Line Items]
EEH Units and Class B Common Stock converted to Class A Common Stock (in shares)			135,621