Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Summary of Significant Accounting Policies [Abstract]

Revision of EPS Presentation

This resulted in immaterial revisions to previously reported basic EPS for Class A and Class B common stock and diluted EPS for the Class B common stock as summarized below:

For the year ended December 31, 2011:	As  previously reported		As revised
Basic EPS – Class A common	$	3.01	$	3.68
Basic EPS – Class B common	$	3.01	$	1.84
Diluted EPS – Class A common	$	3.01	$	3.01
Diluted EPS – Class B common	$	3.01	$	1.84
For the year ended December 31, 2010:	As previously reported		As revised
Basic EPS – Class A common	$	2.45	$	3.00
Basic EPS – Class B common	$	2.45	$	1.50
Diluted EPS – Class A common	$	2.45	$	2.45
Diluted EPS – Class B common	$	2.45	$	1.50