Subsequent Events - Additional Information (Narrative) (Details) (Subsequent Events, USD $)	0 Months Ended
	Jan. 30, 2015
Class A Stock
Subsequent Events [Line Items]
Date of announcement of dividend	Jan. 30, 2015
Quarterly dividend payable amount per share	$ 0.11
Date of payment of dividend	Feb. 27, 2015
Date of record of dividend	Feb. 13, 2015
Class B Stock
Subsequent Events [Line Items]
Date of announcement of dividend	Jan. 30, 2015
Quarterly dividend payable amount per share	$ 0.11
Date of payment of dividend	Feb. 27, 2015
Date of record of dividend	Feb. 13, 2015