Revolving Credit Facility (Details) - USD ($) $ in Thousands		Apr. 25, 2019	Apr. 18, 2019	Mar. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Credit facility balance				$ 46,500	$ 0
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit agreement, maximum loan amount				2,500,000
Line of credit facility, current borrowing base				1,500,000
Line of credit agreement, aggregate lender commitments				1,000,000	1,000,000
Credit facility balance	[1]			46,500	0
Letters of credit	[2]			0	200
Available borrowing capacity				953,500	999,800
Unamortized deferred financing costs				$ 6,000	$ 6,400
Line of Credit | Revolving Credit Facility | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing base			$ 1,600,000
Line of credit agreement, aggregate lender commitments		$ 1,200,000	$ 1,200,000
Credit facility balance		40,000
Letters of credit	[2]	0
Available borrowing capacity		$ 1,160,000

[1] (1) Unamortized deferred financing costs attributable to the credit facility are presented as a component of other noncurrent assets on the accompanying balance sheets and totaled $6.0 million and $6.4 million as of March 31, 2019, and December 31, 2018, respectively. These costs are being amortized over the term of the credit facility on a straight-line basis.

[2] (2) Letters of credit outstanding reduce the amount available under the credit facility on a dollar-for-dollar basis. The letter of credit outstanding as of December 31, 2018, was released during the quarter ended March 31, 2019.