Principal Accounting Policies (Schedule Of Allowance For Revenue Adjustments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounting Policies [Abstract]
Balance at beginning of period	$ 13,816	$ 16,920	$ 14,291
Additions Charged to expense	0	0	0
Additions Charged to other accounts - Revenue	74,481	77,310	86,853
Write-offs	(76,082)	(80,414)	(84,224)
Balance at end of period	$ 12,215	$ 13,816	$ 16,920