Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts [Line Items]
Allowance for Doubtful Accounts, Balance at Beginning of Period	$ 794	$ 797	$ 733
Charged to Costs and Expenses	134	526	560
Write Off of Uncollectible Accounts,Net of Recoveries	(351)	(529)	(496)
Allowance for Doubtful Accounts, Balance at End of Period	$ 577	$ 794	$ 797