Significant Accounting Policies (Summary Of Activity Relating To Allowance For Doubtful Accounts) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Significant Accounting Policies [Line Items]
Beginning Balance	$ 1,160	$ 1,451	$ 2,667
Charges to costs and expenses	1,469	410	455
Recoveries/write-offs	(516)	(701)	(1,671)
Ending Balance	$ 2,113	$ 1,160	$ 1,451