Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, plant and equipment
Land	$ 7,878	$ 8,287
Building improvements	650,480	654,585
Capitalized leases for machinery, equipment and buildings	54,968	30,648
Property, plant and equipment, gross	713,326	693,520
Accumulated depreciation and amortization	(524,806)	(514,509)
Property Plant and Equipment Net before Construction in Progress	188,520	179,011
Construction in Progress	28,276	16,988
Property, plant and equipment, net	216,796	195,999
Operating Leases, Rent Expense	$ 16,800	$ 14,300	$ 11,200