Revenue from Contracts with Customers - Summary of Specified Types of Revenue Expected to be Recognized in Future Related to Unsatisfied Performance Obligations (Detail 1) $ in Thousands	Sep. 30, 2019 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue remaining performance obligation	$ 38,931
Mobilization and Contract Preparation Revenue [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue remaining performance obligation	3,740
Capital Modification Revenue [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue remaining performance obligation	6,774
Blended Rate Revenue [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue remaining performance obligation	$ 28,417