Stockholders' Equity (Dividends Paid On Common Stock) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 15, 2013	Mar. 23, 2013	Jun. 16, 2012	Mar. 24, 2012	Jun. 15, 2013	Jun. 16, 2012
Dividends Payable [Line Items]
Date Paid	Apr. 11, 2013	Dec. 31, 2012	Apr. 12, 2012	Jan. 12, 2012
Per-Share Amounts	$ 0.175	$ 0.175	$ 0.145	$ 0.145
Total	$ 42.2	$ 41.9	$ 36.3	$ 43.8	$ 84.1	$ 80.1
Dividends Paid On Common Stock Member
Dividends Payable [Line Items]
Record Date	Mar. 25, 2013	Dec. 17, 2012	Mar. 29, 2012	Dec. 22, 2011