Restructuring And Asset Impairment Charges (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 employees Locations	Sep. 30, 2011	Sep. 30, 2012 employees Locations branches		Sep. 30, 2011	Dec. 31, 2011 employees branches	Dec. 31, 2007 employees Locations
Restructuring Cost and Reserve [Line Items]
Employee headcount (in employees)	11,200		11,200			7,500	10,900
Number of locations (in locations)	848		848			529	697
Restructuring charge	$ 40	$ 2	$ 93	[1]	$ 5
Asset impairment charges	10		13		1
Current Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charge			91	[1]
Scenario, Forecast [Member] | Acquisition [Member] | Minimum [Member] | RSC [Member] | Current Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charge			10	[1]
Scenario, Forecast [Member] | Acquisition [Member] | Maximum [Member] | RSC [Member] | Current Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charge			$ 30	[1]

[1] Reflected in our condensed consolidated statements of income as “Restructuring charge.” These charges are not allocated to our reportable segments.