Common Stock (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 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)	29,031,504		29,031,504		28,696,321
Common stock, shares outstanding (in shares)	29,031,504		29,031,504		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 (in shares)	176,655	339,075	402,056	454,011
Common stock repurchased (in shares)	43,344	83,762	102,605	112,426
Class B Common Stock
Capital Unit [Line Items]
Common stock, shares issued (in shares)	35,416,446		35,416,446		35,452,178
Common stock, shares outstanding (in shares)	35,416,446		35,416,446		35,452,178
EEH Units and Class B Common Stock converted to Class A Common Stock (in shares)	35,732	11,195	35,732	205,241