Property, plant and equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 556,010		$ 539,584
Less: Accumulated depreciation and amortization	(144,741)		(132,374)
Total Property, plant and equipment, net	411,269		407,210
Depreciation and amortization	12,373	$ 10,166
Land and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	21,848		21,843
Buildings, Building Improvements and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	159,267		160,005
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	210,979		206,819
Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	51,562		50,829
Construction-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 112,354		$ 100,088