Debt Credit Agreement (Details) - USD ($)	Oct. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Apr. 30, 2019	Dec. 19, 2018
Revolving Credit Facility | Third Amended Credit Agreement
Debt Instrument [Line Items]
Increase in borrowing base				$ 900,000,000.0
Maximum borrowing commitment		$ 500,000,000.0
Maximum facility amount		$ 1,500,000,000
Line of Credit | San Mateo Credit Facility
Debt Instrument [Line Items]
Maximum borrowing commitment			$ 325,000,000.0		$ 250,000,000.0
Line of credit, accordian feature					$ 400,000,000.0
Subsequent Event | Line of Credit | San Mateo Credit Facility
Debt Instrument [Line Items]
Maximum borrowing commitment	$ 375,000,000.0