Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Operating Leases:
Operating Lease Right-of-Use Asset	$ 205,647	$ 0
Current Portion of Operating Lease Obligations	65,061	0
Operating Lease Obligations	122,514	$ 0
Total Operating Lease Liabilities	187,575
Finance Leases:
Property, Plant and Equipment	73,363
Less—Accumulated Depreciation, Depletion and Amortization	62,191
Property, Plant and Equipment—Net	11,172
Current Portion of Finance Lease Obligations	7,203
Finance Lease Obligations	9,400
Total Finance Lease Liabilities	$ 16,603