Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Allowance for doubtful accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 64		$ 33		$ 29
Acquired	0		13		0
Charged to Costs and Expenses	4		37		21
Deductions	19	[1]	19	[1]	17	[1]
Balance at End of Period	49		64		33
Reserve for obsolescence and shrinkage [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	3		2		1
Acquired	0		1		0
Charged to Costs and Expenses	16		13		5
Deductions	16	[2]	13	[2]	4	[2]
Balance at End of Period	3		3		2
Self-insurance reserve [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	97		83		93
Acquired	0		21		0
Charged to Costs and Expenses	92		84		65
Deductions	95	[3]	91	[3]	75	[3]
Balance at End of Period	$ 94		$ 97		$ 83

[1] Represents write-offs of accounts, net of recoveries.

[2] Represents write-offs.

[3] Represents payments.