Stockholders Equity and Equity Compensation Plans (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Stockholders Equity and Equity Compensation Plans (Additional Textual) [Abstract]
Shares repurchased	300,000	300,000
Total amount paid	$ 6.5	$ 5.2
Weighted-average price per share	$ 19.80	$ 15.84
Remaining number of shares available for repurchase	2,300,000
Repurchase of common stock employee tax withholding obligation, shares	200,000	200,000
Repurchase of common stock for tax withholdings, value	4.8	2.9
Performance based awards granted to executive management shares	175,384
Stock-based compensation expense	$ 3.6	$ 3.1
Restricted common stock
Stockholders' Equity and Equity Compensation Plans (Textual) [Abstract]
Common stock shares issued to members of executive management vesting installments	4 years
Performance Shares
Stockholders' Equity and Equity Compensation Plans (Textual) [Abstract]
Common stock shares issued to members of executive management vesting installments	3 years