Leases (Summary of Amounts Recognized in Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Assets
Operating lease assets	$ 85,766	$ 0	$ 0
Finance lease assets, property, plant and equipment, net	25,379
Total leased assets	114,941
Liabilities
Current operating leases	28,017
Non-current operating leases	57,451	0	0
Total operating lease liabilities	85,468
Current finance leases	6,007	0	0
Non-current finance leases	23,058	$ 0	$ 0
Total finance lease liabilities	29,065
Total lease liabilities	114,533
Rail
Assets
Finance lease assets, property, plant and equipment, net	$ 3,796