Basis of Presentation and Significant Accounting Policies - Allowance for doubtful accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Shipping, Handling and Transportation Costs	$ 35,171	$ 36,585	$ 35,214
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of year	3,529	3,584	3,848
Add Provision charged to expense	484	1,420	523
Add Recoveries	173	90	140
Add Other	0	0	157
Less Charges against allowance	(723)	(1,565)	(1,084)
Balance, end of year	$ 3,463	$ 3,529	$ 3,584