Equity Incentive Plans Equity Incentive Plans (Schedule of Nonvested Shares Unamortized Share-based Compensation Expense to be Recognized in the Future) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested shares unamortized share-based compensation expense to be recognized in 2012	$ 2,956
Nonvested shares unamortized share-based compensation expense to be recognized in 2013	1,714
Nonvested shares unamortized share-based compensation expense to be recognized in 2014	836
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options	$ 5,506