Capital Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		1 Months Ended			0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Feb. 28, 2014 Class A Common Stock	Mar. 31, 2014 Class A Common Stock	Dec. 31, 2013 Class A Common Stock	Jan. 24, 2014 Class A Common Stock 2006 Equity Compensation Plan [Member]	Mar. 31, 2014 Class A Common Stock Share Repurchase Program [Domain]	Mar. 31, 2014 Class B Common Stock	Dec. 31, 2013 Class B Common Stock
Class of Stock [Line Items]
Common Stock, Shares, Outstanding				20,343,161	19,868,018			24,046,934	24,287,045
Stock Repurchased and Retired During Period, Shares			100,355
Payments for Repurchase of Common Stock	$ 3,159	$ 448	$ 2,538
Stock Repurchase Program, Remaining Authorized Repurchase Amount							1,899,645
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized						1,500,000