Capital Stock (Details) (USD $) In Thousands, unless otherwise specified					3 Months Ended
	Mar. 31, 2013 Class A Common Stock	Dec. 31, 2012 Class A Common Stock	Mar. 31, 2013 Class B Common Stock	Dec. 31, 2012 Class B Common Stock	Mar. 31, 2013 Series A Preferred Stock [Member]
Class of Stock [Line Items]
Common Stock, Shares, Outstanding	18,424,252	17,635,369	25,190,690	25,654,954
Preferred Stock, Aggregate Redemption Price					$ 50,150