Cash Discounts And Doubtful Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Cash Discounts [Roll Forward]
Beginning Balance, Allowance for Cash Discounts	$ 1,498	$ 1,373	$ 1,201
Provision (Charged to Expense), Allowance for Cash Discounts	21,228	20,440	17,854
Deductions, Allowance for Cash Discounts	(21,315)	(20,315)	(17,682)
Ending Balance, Allowance for Cash Discounts	1,411	1,498	1,373
Allowance for Doubtful Accounts
Beginning Balance, Allowance for Doubtful Accounts	6,266	5,926	5,016
Provision (Charged to Expense), Allowance for Doubtful Accounts	4,379	5,537	6,401
Deductions, Allowance for Doubtful Accounts	(5,188)	(5,197)	(5,491)
Ending Balance, Allowance for Doubtful Accounts	5,457	6,266	5,926
Allowance for Cash Discounts and Doubtful Accounts
Beginning Balance, Allowance for Cash Discounts and Doubtful Accounts, Total	7,764	7,299	6,217
Provision for Cash Discounts and Doubtful Accounts	25,607	25,977	24,255
Deductions, Allowance for Cash Discounts and Doubtful Accounts	(26,503)	(25,512)	(23,173)
Ending Balance, Allowance for Cash Discounts and Doubtful Accounts, Total	$ 6,868	$ 7,764	$ 7,299