Schedule of Valuation and Qualifying Accounts (Details) (Allowance for doubtful accounts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Allowance for doubtful accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 3,297		$ 3,917		$ 10,805
Charged (Credited) to Expenses or Other Accounts, Net	0		368		(4,404)
Deductions and Adjustments	(417)	[1]	(988)	[1]	(2,484)	[1]
Balance at End of Year	$ 2,880		$ 3,297		$ 3,917

[1] Deductions and adjustments for the allowances primarily relate to accounts written off.