Employee Benefit and Incentive Plans (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock-Based Incentive Plans
Outstanding, shares	897,555
1997 Director Plan Restricted Class A Common Stock
Stock-Based Incentive Plans
Beginning balance
Granted
Vested, deferred or forfeited
Outstanding, shares
2007 Plan Restricted Class A Common Stock
Stock-Based Incentive Plans
Beginning balance	244,424
Granted	100,000
Vested, deferred or forfeited	(344,424)
Outstanding, shares
2011 Plan Restricted Class A Common Stock
Stock-Based Incentive Plans
Beginning balance
Granted	275,000
Vested, deferred or forfeited	(275,000)
Outstanding, shares
Restricted Class A Common Stock Plans
Stock-Based Incentive Plans
Beginning balance	244,424
Granted	375,000
Vested, deferred or forfeited	(619,424)
Vested		(88,361)	(53,188)
Outstanding, shares		244,424
1997 Director Plan Stock Units
Stock-Based Incentive Plans
Beginning balance	68,544
Granted and deferred
Vested	(18,911)
Outstanding, shares	49,633
2007 Plan Stock Units
Stock-Based Incentive Plans
Beginning balance	438,260
Granted and deferred	60,000
Vested	(218,040)
Outstanding, shares	280,220
2011 Plan Stock Units
Stock-Based Incentive Plans
Beginning balance	55,531
Granted and deferred	554,155
Vested	(41,984)
Outstanding, shares	567,702
Stock Units Plans
Stock-Based Incentive Plans
Beginning balance	562,335
Granted and deferred	614,155
Vested	(278,935)
Outstanding, shares	897,555
1997 Director Plan
Stock-Based Incentive Plans
Outstanding, shares	49,633
2007 Plan
Stock-Based Incentive Plans
Outstanding, shares	280,220
2011 Plan
Stock-Based Incentive Plans
Outstanding, shares	567,702