Equity - Activity for Class B Common Stock and Treasury Stock (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	8,439,747	8,264,583	8,375,077	8,702,074
Stock Award Activity (in shares)	(56,750)	(22,750)	(706,331)	(521,074)
Purchase of Treasury Stock (in shares)	843,416	52,600	1,557,667	113,433
Ending Balance (in shares)	9,226,413	8,294,433	9,226,413	8,294,433
Class B Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	101,065,709	101,240,873	101,130,379	100,803,382
Stock Award Activity (in shares)	56,750	22,750	706,331	521,074
Purchase of Treasury Stock (in shares)	(843,416)	(52,600)	(1,557,667)	(113,433)
Ending Balance (in shares)	100,279,043	101,211,023	100,279,043	101,211,023
Purchase of Treasury Stock (in shares)			1,600,000