Stockholders' Equity, Share Rollforward (Details) - shares		12 Months Ended
	Aug. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Shares outstanding at beginning of year		20,968,707
Stock issued	7,590,000
Shares outstanding at end of year		21,036,087	20,968,707
Common Stock [Member]
Class of Stock [Line Items]
Shares outstanding at beginning of year		20,968,707	0	0
Shares issued from equity-based compensation		67,380	0	0
Reclassification		0	15,968,707	0
Stock issued		0	5,000,000	0
Shares outstanding at end of year		21,036,087	20,968,707	0
Class A Common Stock [Member]
Class of Stock [Line Items]
Shares outstanding at beginning of year		0	13,803,183	13,795,530
Reclassification		0	(22,421,146)	0
Share dividend		0	8,617,963	0
Other		0	0	7,653
Shares outstanding at end of year		0	0	13,803,183
Class B Common Stock [Member]
Class of Stock [Line Items]
Shares outstanding at beginning of year		0	1,513,592	1,287,696
Reclassification		0	(1,783,858)	0
Restricted stock grants vested		0	270,266	225,896
Shares outstanding at end of year		0	0	1,513,592