Earnings per Share Weighted Average Class B Shares and New Class A Units Excluded (Details) (Weighted Average Class B Shares and New Class A Units [Member]) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Weighted Average Class B Shares and New Class A Units [Member]
Weighted Average Class B Shares and New Class A Unit [Line Items]
Weighted Average Class B Shares and New Class A Units	4,466	10,883	12,703