Consolidating Valuation and Qualifying Accounts Consolidating 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, beginning of period	$ 76	$ 84	$ 20
Additional charged to costs and expenses	20	54	77
Write-offs	50	62	13
Balance, end of period	$ 46	$ 76	$ 84