Stockholders Equity (Share Repurchase Program) (Details) (Common Class A, USD $)	0 Months Ended	12 Months Ended	0 Months Ended	3 Months Ended	5 Months Ended
	Nov. 08, 2011 2011 Stock Repurchase Program	Dec. 31, 2013 2011 Stock Repurchase Program	Nov. 12, 2013 2013 Stock Repurchase Program	Mar. 31, 2014 2013 Stock Repurchase Program	Mar. 31, 2014 2013 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount	$ 50,000,000		$ 60,000,000
Treasury stock acquisition		$ 35,600,000			$ 5,900,000
Stock repurchase program, shares acquired during period				90,978	107,073
Stock repurchase program, shares acquired during period, weighted-average cost per share				$ 54.80