Business, Basis Of Presentation And Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Nov. 15, 2011
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Accumulated other comprehensive loss	$ (7,946,000)	$ (6,156,000)
Restricted Cash Description	Restricted cash as of December 31, 2010 included in cash and cash equivalents was invested in certificates of deposit with maturities equal to or less than 90 days
Cash overdrafts	14,900,000
Credit loss estimates	Credit loss estimates are derived by comparing the estimated fair value of the securities, which are based on a number of factors, including estimated probabilities of default, with the value that would have been derived if the probability of default for the same securities were zero percent. The difference between the recorded fair value and the estimated fair value assuming a zero probability of default is considered the portion of total decline in fair value attributable to credit losses.
Net deferred financing costs	8,200,000	11,200,000
Impairment charges for long-lived assets held for use	0	0	0
Restricted cash		18,000,000
Multi-employer pension plan withdrawal liability	6,400,000			6,400,000
Line of credit facility, expiration date	August 22, 2016
Workers' Compensation Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Insurance policies subject to per claim deductibles	1,000,000
General Liability Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Insurance policies subject to per claim deductibles	2,000,000
Automobile Liability Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Insurance policies subject to per claim deductibles	2,000,000
Umbrella Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Maximum coverage amount	100,000,000
Employee Group Health Claims Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Annual per employee maximum losses	400,000
Liability for unpaid claims and claims adjustment expense, reported and incurred but not reported (IBNR) claims, total	1,400,000	1,400,000
Workers Compensation General And Automobile Policies [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Liability for unpaid claims and claims adjustment expense, reported and incurred but not reported (IBNR) claims, total	39,100,000	36,300,000
Auction Rate Securities [Member] | Structured Finance Securities [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Investment, debt security, default rate of underlying assets	5.56%
Auction Rate Securities [Member] | Structured Finance Securities [Member] | Minimum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Investment, debt security, default rate of underlying assets	8.00%
Auction Rate Securities [Member] | Structured Finance Securities [Member] | Maximum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Investment, debt security, default rate of underlying assets	9.00%
Standby Letters Of Credit [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Insurance carriers letters of credit, amount outstanding	51,400,000	59,500,000
Insurance Surety Bond [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Surety bonds related to self-insurance programs	7,100,000	4,600,000
Stock Options [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Share-based compensation arrangement expiration date	have a term not to exceed ten years
Stock Options [Member] | Minimum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Vesting period	one
Stock Options [Member] | Maximum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Vesting period	five
Restricted Share Award [Member] | Minimum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Vesting period	from day of issuance
Restricted Share Award [Member] | Maximum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Vesting period	five years
Computer Software, Intangible Asset [Member] | Maximum [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Software capitalization amortized period	amortized over a period not to exceed seven years
Letters Of Credit [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Maximum amount of available borrowing capacity	$ 600,000,000