Common Stock (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
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)	28,862,461		28,696,321
Common stock, shares outstanding (in shares)	28,862,461		28,696,321
Class A Common Stock | Bold Contribution Agreement
Capital Unit [Line Items]
Stock conversion (in shares)	1
Class A Common Stock | 2014 Plan
Capital Unit [Line Items]
Common shares issued during period under stock plan	225,401	114,936
Common stock repurchased	59,261	28,664
Class B Common Stock
Capital Unit [Line Items]
Common stock, shares issued (in shares)	35,452,178		35,452,178
Common stock, shares outstanding (in shares)	35,452,178		35,452,178
EEH Units and Class B Common Stock converted to Class A Common Stock (in shares)	0	194,046