Income Taxes (Schedule Of Income Tax Provision) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Income before provision for income taxes	$ 116.4	$ 115.3	$ 109.2	$ 80.0	$ 103.5	$ 102.2	$ 97.4	$ 95.1	$ 420.9	$ 398.2	$ 343.1
Current provision for income taxes, Federal									90.9	128.4	94.9
Current provision for income taxes, State									7.3	7.4	3.5
Current provision for income taxes									98.2	135.8	98.4
Deferred provision for income taxes, Federal									52.0	8.7	23.6
Deferred provision for income taxes, State									4.1	0.1	1.4
Deferred provision for income taxes									56.1	8.8	25.0
Interest									0.4	0.5	0
Unrecognized Tax Benefits, Income Tax Penalties Expense									0	0	0
Interest and penalties expense (benefit)									0.4	0.5	0
Provision for income taxes	$ 43.4	$ 41.3	$ 39.8	$ 30.2	$ 37.6	$ 37.1	$ 35.9	$ 34.5	$ 154.7	$ 145.1	$ 123.4