Summary of Significant Accounting Policies (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts Receivable
Balance, beginning of year	$ 2,421	$ 1,837	$ 2,036
Additions (reductions) to expense	1,039	844	(58)
Write-offs	(174)	(239)	(103)
Other	(139)	(21)	(38)
Balance, end of year	$ 3,147	$ 2,421	$ 1,837