Stockholders' Equity Stockholders' Equity (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2009	Dec. 31, 2011	Apr. 30, 2007
Stockholders' Equity Note [Abstract]
Stock Issued During Period, Shares, New Issues		5,520,000
Stock Issued During Period, Value, New Issues		$ 87,700,000
Underwriting Discounts and Commissions		4,600,000
Other Indirect Cost In Connection With Public Offering		127,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			1,400,000
Stock Repurchased During Period, Shares	250,158
Stock Repurchased During Period, Value	$ 2,500,000