Common Stock (Details) $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 17, 2018 shares	May 09, 2017 USD ($) class_of_stock shares	Oct. 31, 2018 shares	Sep. 30, 2018 USD ($) shares	Sep. 30, 2017 shares	Sep. 30, 2018 USD ($) shares	Sep. 30, 2017 shares	Dec. 31, 2017 USD ($) shares
Bold Contribution Agreement
Capital Unit [Line Items]
Number of classes of common stock | class_of_stock		2
Member Units | Bold Contribution Agreement
Capital Unit [Line Items]
Stock conversion (in shares)						1
Class A Common Stock
Capital Unit [Line Items]
Common stock, shares issued (in shares)				28,400,421		28,400,421		27,584,638
Common stock, shares outstanding (in shares)				28,400,421		28,400,421		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
Common stock issued, value | $		$ 2,000
Stock conversion (in shares)		1				1
Class A Common Stock | 2014 Plan
Capital Unit [Line Items]
Common shares issued during period under stock plan				115,574	126,751	569,585	594,380
Treasury Stock, Common, Shares				30,511	29,441	142,937	29,441,000
Class B Common Stock
Capital Unit [Line Items]
Common stock, shares issued (in shares)				35,663,034		35,663,034		36,052,169
Common stock, shares outstanding (in shares)				35,663,034		35,663,034		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)				183,894		389,135
Class B Common Stock | Bold Contribution Agreement
Capital Unit [Line Items]
Stock conversion (in shares)		1
Subsequent Event
Capital Unit [Line Items]
Common shares issued during period under stock plan	32,315,695
Subsequent Event | Class B Common Stock
Capital Unit [Line Items]
Common shares issued during period under stock plan	32,315,695
EEH Units and Class B Common Stock converted to Class A Common Stock (in shares)			210,856