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Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

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Leases - Capital leases (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Leases - Capital leases (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Capital Leases, Future Minimum Payments Due, Rolling Maturity [Abstract]
2021	$ 22,246		$ 22,246
2022	714		714
Total	22,960		22,960
Less amount representing interest	(128)		(128)
Capital lease obligations	22,832		22,832
Current portion	(22,198)		(22,198)		$ (19,750)
Noncurrent	634		634
Equipment under capital leases
Equipment under capital leases
Cost of equipment under capital leases	42,100		42,100		39,100
Accumulated depreciation of equipment under capital leases	12,600		12,600		$ 11,700
Maximum
Capital Leased Assets [Line Items]
Interest expense related to capital leases	$ 100	$ 100	$ 100	$ 100