Summary of Significant Accounting Policies (Schedule of Stock by Class) (Details)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Common Class A [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding	60,794,114		60,591,030		58,434,704
Stock Issued During Period, Shares, Conversion of Convertible Securities			300,000		1,750,000
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	(241,441)	[1]	(96,916)	[1]	406,326	[1]
Common Stock, Shares, Outstanding	60,552,673		60,794,114		60,591,030
Common Class B [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding	11,484,408		11,784,408		13,534,408
Stock Issued During Period, Shares, Conversion of Convertible Securities			(300,000)		(1,750,000)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	0	[1]	0	[1]	0	[1]
Common Stock, Shares, Outstanding	11,484,408		11,484,408		11,784,408

[1] *Reflects common stock activity in connection with employee stock option exercises and restricted shares granted to employees, as well as in connection with the fulfillment of employees’ statutory tax withholding obligations for applicable income and other employment taxes and forfeited employee restricted shares.