Common Stock and Treasury Stock (Details) - shares shares in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Class A Common Stock [Member]
Common Stock [Line Items]
Balance, shares	6,446	6,409
Exercised options	93	7
Conversion of shares	32	3
Issuance of restricted stock		27
Forfeitures of restricted stock	(2)
Balance, shares	6,569	6,446
Class B Common Stock [Member]
Common Stock [Line Items]
Balance, shares	843	816
Exercised options	32	0
Conversion of shares	(32)	(3)
Issuance of restricted stock		30
Forfeitures of restricted stock	0
Balance, shares	843	843