Trade Accounts Receivable, Net Of Allowances (Schedule Of Unbilled Trade Accounts Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 99,219	$ 81,055
Allowance for sales credit memos	(895)	(1,027)
Allowance for doubtful accounts	(31)	(132)
Total allowance	(926)	(1,159)
Total accounts receivable, net	98,293	79,896
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	77,123	65,373
Unbilled Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 22,096	$ 15,682