Revenue Recognition - Additional Information (Detail) - Vessel Mobilization - USD ($) $ in Millions	Dec. 31, 2019	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Deferred costs included within other current assets and other assets		$ 3.9
Other Assets
Disaggregation of Revenue [Line Items]
Deferred costs included within other current assets and other assets		$ 0.5
Unsatisfied Performance Obligations | Scenario, Forecast
Disaggregation of Revenue [Line Items]
Deferred mobilization revenue included within other current liabilities	$ 0.4