Stockholders' Equity and Equity Compensation Plans (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Stockholders Equity and Equity Compensation Plans (Additional Textual) [Abstract]
Repurchased common stock, shares			800,000	600,000
Repurchased common stock, value			$ 13.3	$ 7.7
Weighted-average price of common stock			$ 16.23	$ 13.25
Total remaining number of shares available for repurchase	2,600,000		2,600,000
Repurchase of Common Stock For Tax Withholdings, shares			200,000	200,000
Repurchase of Common Stock For Tax Withholdings, value			3.0	4.2
Performance Based Awards Granted To Executive Management, Shares			150,313
Stock-based compensation expense	$ 3.5	$ 3.2	$ 10.0	$ 9.7
Restricted common stock [Member]
Stockholders' Equity and Equity Compensation Plans (Textual) [Abstract]
Common stock shares issued to members of executive management vesting installments			4 years
Performance-based awards [Member]
Stockholders' Equity and Equity Compensation Plans (Textual) [Abstract]
Common stock shares issued to members of executive management vesting installments			3 years