(Details) (USD $)	12 Months Ended
	Dec. 31, 2011 lawsuits	Dec. 31, 2010 lawsuits	Dec. 31, 2009	Dec. 31, 2006 lawsuits
Purchase Commitment, Remaining Minimum Amount Committed	$ 103,800,000
Operating and Capital Lease Commitments [Abstract]
Total rental expense under all operating leases	8,100,000		9,000,000
2011	8,487,000
2012	7,236,000
2013	4,380,000
2014	3,175,000
2015	2,639,000
2016 and thereafter	10,777,000
Total	36,694,000
Purchase Obligations [Abstract]
Purchase Commitment, Remaining Minimum Amount Committed	$ 103,800,000
Legal Proceedings [Abstract]
Number of Shareholder Derivative Lawsuits Filed				3
Derivative lawsuits pending	1
New shareholder derivative lawsuits filed	1	1		4