Stock Incentive Plan (Schedule of Share-based Compensation, Stock Options, Activity) (Details) (Stock Options [Member], USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of year	3,503,384		5,700,552		6,566,377
Oustanding at beginning of year (Price)	$ 10.42	[1]	$ 9.53	[1]	$ 9.06	[1]
Exercised	2,185,952		2,191,260		860,074
Exercised (Price)	$ 10.05	[1]	$ 8.11	[1]	$ 5.93	[1]
Cancelled	3,375		5,908		5,751
Cancelled (Price)	$ 10.07	[1]	$ 10.07	[1]	$ 10.85	[1]
Outstanding at year end	1,314,057		3,503,384		5,700,552
Outstanding at end of year (Price)	$ 11.04	[1]	$ 10.42	[1]	$ 9.53	[1]

[1] Weighted average exercise price.