Summary of Significant Accounting Policies (Schedule of Stock by Class) (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common Class A [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding	60,552,673	60,794,000	60,591,000
Conversion of Stock, Amount Converted			300,000
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	(357,000)	(241,000)	(97,000)
Common Stock, Shares, Outstanding	60,909,831	60,552,673	60,794,000
Common Class B [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding	11,484,408	11,484,000	11,784,000
Conversion of Stock, Amount Converted			(300,000)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	0	0	0
Common Stock, Shares, Outstanding	11,484,408	11,484,408	11,484,000