Property and Equipment, Net - Property and Equipment Table (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 439,750	$ 419,440
Less: Accumulated depreciation	227,620	213,290
Property and equipment, net	212,130	206,150
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,520	5,520
Building [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	63,500	61,960
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 370,730	$ 351,960