Stockholders' Equity (Dividends Declared on Common Stock) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended						6 Months Ended		9 Months Ended
	Sep. 06, 2014	Jun. 14, 2014	Mar. 22, 2014	Sep. 07, 2013	Jun. 15, 2013	Mar. 23, 2013	Jun. 14, 2014	Jun. 15, 2013	Sep. 06, 2014	Sep. 07, 2013
Dividends Payable [Line Items]
Date Declared	Aug. 21, 2014	May 14, 2014	Mar. 12, 2014	Aug. 22, 2013	May 14, 2013	Mar. 14, 2013
Per-Share Amounts	$ 0.23	$ 0.23	$ 0.20	$ 0.2	$ 0.2	$ 0.175
Total	$ 53.2	$ 53.1	$ 46.2	$ 49.1	$ 48.2	$ 42.2	$ 99.3	$ 90.4	$ 152.5	$ 139.5
Dividends Declared On Common Stock
Dividends Payable [Line Items]
Record Date	Sep. 18, 2014	Jun. 19, 2014	Mar. 24, 2014	Sep. 19, 2013	Jun. 20, 2013	Mar. 25, 2013