Stockholders' Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		9 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Open Market Repurchase Program for Common Stock, Adopted December 14, 2011 [Member]	Sep. 30, 2012 Open Market Repurchase Program for Common Stock, Adopted September 15, 2010 [Member]	Sep. 30, 2011 Open Market Repurchase Program for Common Stock, Adopted September 15, 2010 [Member]	Sep. 30, 2012 Open Market Repurchase Program for Common Stock, Adopted September 15, 2010 [Member]	Sep. 30, 2011 Open Market Repurchase Program for Common Stock, Adopted September 15, 2010 [Member]
Class of Stock [Line Items]
Total capital stock, shares authorized	400,000,000
Common stock, shares authorized	300,000,000	300,000,000
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred Stock, Shares Outstanding	0
Preferred stock, par value per share	$ 0.01	$ 0.01
Common stock, par value per share	$ 0.01	$ 0.01
Maximum number of shares authorized for repurchase			4,000,000	4,000,000		4,000,000
Maximum value of shares authorized under repurchase program			$ 100			$ 100
Number of shares repurchased and retired			0	0	1,706,300	0	3,469,866
Weighted average price of repurchased and retired shares, per share					$ 20.93		$ 24.68
Cumulative number of shares repurchased and retired						3,921,138
Cumulative weighted average price of repurchased and retired shares, per share						$ 25.39
Maximum amount of dividends or stock repurchases permissable under the Credit Facility	50
Amount available for dividend payments, stock repurchases or Senior Notes repurchases at period end	$ 85.8