Income Taxes (Deferred Tax Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Abstract]
Inventory valuation adjustments	$ 15.9	$ 10.6
Insurance reserves	14.4	14.6
Reserve for estimated wireless service deactivations	14.1	8.9
Deferred revenue	13.4	7.9
Foreign branch net operating losses	12.1	7.1
Indirect effect of unrecognized tax benefits	11.6	11.1
Deferred compensation	10.1	12.2
Stock-based compensation	8.0	8.6
Accrued average rent	7.6	8.7
State net operating loss, net of federal benfit	5.8	1.2
Other	15.0	11.9
Gross deferred tax assets	128.0	102.8
Valuation allowance	(80.9)	(7.1)
Total deferred tax assets	47.1	95.7
Depreciation and amortization	29.7	8.7
Deferred taxes on foreign operations	4.0	4.1
Other	10.7	11.4
Total deferred tax liabilities	44.4	24.2
Net deferred tax assets	$ 2.7	$ 71.5