Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Significant Accounting Policies [Line Items]
Percentage of fair value in excess of carrying amount	15.00%
Deferred revenue	$ 26,000,000	$ 16,000,000
Advertising expense	0	0	2,000,000
Insurance stop loss limit, self insured events	600,000
Percent threshold used to define more likely than not for tax purposes	50.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	2.00%	2.00%
General Liability [Member]
Significant Accounting Policies [Line Items]
Insurance deductible, per occurence	2,000,000	2,000,000
Workers Compensation [Member]
Significant Accounting Policies [Line Items]
Insurance deductible, per occurence	1,000,000	1,000,000
Automobile Liability [Member]
Significant Accounting Policies [Line Items]
Insurance deductible, per occurence	2,000,000	2,000,000
Trade Names and Trademarks [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets life	5 years
Assets Leased to Others [Member]
Significant Accounting Policies [Line Items]
PP&E additions	24,000,000	10,000,000	12,000,000
Cost of services, maintenance costs	$ 455,000,000	$ 291,000,000	$ 262,000,000
Minimum [Member] | Non-Compete Agreements [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets life	2 years
Minimum [Member] | Customer Relationships [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets life	8 years
Minimum [Member] | Assets Leased to Others [Member]
Significant Accounting Policies [Line Items]
PP&E salvage value	0.00%
PP&E useful life	2 years
Minimum [Member] | Other Capitalized Property Plant and Equipment [Member]
Significant Accounting Policies [Line Items]
PP&E useful life	2 years
Maximum [Member] | Revenue [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage	1.00%	1.00%	1.00%
Maximum [Member] | Non-Compete Agreements [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets life	5 years
Maximum [Member] | Customer Relationships [Member]
Significant Accounting Policies [Line Items]
Finite lived intangible assets life	15 years
Maximum [Member] | Assets Leased to Others [Member]
Significant Accounting Policies [Line Items]
PP&E salvage value	10.00%
PP&E useful life	12 years
Maximum [Member] | Other Capitalized Property Plant and Equipment [Member]
Significant Accounting Policies [Line Items]
PP&E useful life	39 years