Equity Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Oct. 23, 2012
Equity [Abstract]
Increase in common share repurchase authorization			13,200,000
Remaining number of shares authorized to be repurchased	17,000,000		20,000,000
Stock repurchased during period	3,000,000
Payments for repurchase of common stock	$ 71.2	$ 15.9