Stockholders' Equity (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Open Market Repurchase Program for Common Stock, Adopted December 14, 2011 [Member]	Dec. 31, 2012 Open Market Repurchase Program for Common Stock, Adopted September 15, 2010 [Member]	Dec. 31, 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	400,000,000	400,000,000
Common stock, shares authorized	300,000,000	300,000,000	300,000,000
Preferred stock, shares authorized	100,000,000	100,000,000	100,000,000
Preferred stock, shares outstanding	0	0
Preferred stock, par value per share	$ 0.01	$ 0.01	$ 0.01
Common stock, par value per share	$ 0.01	$ 0.01	$ 0.01
Maximum number of shares authorized for repurchase				4,000,000	4,000,000
Maximum value of shares authorized under repurchase program				$ 100,000,000	$ 100,000,000
Period repurchase program in force unless maximum dollar amount of repurchases expended first				3 years	3 years
Number of shares repurchased and retired				0	0	3,469,866
Weighted-average price of repurchased and retired shares, per share						$ 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
Common Stock, Dividends, Per Share, Declared	$ 0.25
Dividends, Common Stock		22,535,000
Maximum amount of dividends or stock repurchases permissable under the Credit Facility		150,000,000
Amount available for dividend payments, stock repurchases or Senior Notes repurchases at period end	$ 178,100,000	$ 178,100,000