Related Party Transactions narrative (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Common Stock Ownership Percentage by a Related Party	5.00%
Number of Board of Directors	15	4	7
Common Class A [Member]
Related Party Transaction [Line Items]
Number of Board of Directors	5
Common stock, Class B Voting
Related Party Transaction [Line Items]
Number of Board of Directors	5