Commitments and Contingent Liabilities (Details) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011
Commitments and Contingent Liabilities (Textuals) [Abstract]
Lease period, minimum	5 years
Lease period, maximum	20 years
Letters of credit outstanding	$ 20,066
Surety bonds posted	$ 17,177