Restricted Cash (Schedule Of Restricted Cash) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	$ 33,761	$ 40,848
Securitization Escrow Accounts [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	21,378	28,583
Payment And Performance Bonds [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	888	873
Surety Bonds And Workers Compensation [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	$ 11,495	$ 11,392