Interim Financial Information - Adoption of ASC Topic 606, "Revenue from Contract with Customers" (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect of Topic 606 on retained earnings	$ 11,397
ASU 2014-09 | Adjustment due to Topic 606 | Maintenance and repair sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect of Topic 606 on retained earnings		$ 4,800
ASU 2014-09 | Adjustment due to Topic 606 | Finance, insurance and other, net
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Effect of Topic 606 on retained earnings		$ 6,600