Common Stock Activity (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	1 Months Ended	3 Months Ended		12 Months Ended
	Jul. 31, 2012	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock repurchase program, amount authorized			$ 150,000,000
Treasury stock acquired, shares	2.0	2.9			4.6
Treasury stock acquired, value	$ 31,200,000	$ 43,800,000		$ 75,000,000	$ 75,000,000