Income Taxes (Schedule Of Income Tax Provision) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Abstract]
Income before provision for income taxes	$ 103.5	$ 102.2	$ 97.4	$ 95.1	$ 91.3	$ 83.8	$ 89.2	$ 78.8	$ 398.2	$ 343.1	$ 296.4
Current provision for income taxes, Federal									128.4	94.9	87.7
Current provision for income taxes, State									7.4	3.5	6.3
Current provision for income taxes									135.8	98.4	94.0
Deferred provision for income taxes, Federal									8.7	23.6	13.3
Deferred provision for income taxes, State									0.1	1.4	2.0
Deferred provision for income taxes									8.8	25.0	15.3
Interest									0.5		(0.7)
Penalties											(0.2)
Interest and penalties expense (benefit)									0.5		(0.9)
Provision for income taxes	$ 37.6	$ 37.1	$ 35.9	$ 34.5	$ 31.4	$ 30.9	$ 32.6	$ 28.5	$ 145.1	$ 123.4	$ 108.4