Equity Method Investments - Schedule of Equity Investments in Affiliates Balance Affected (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 01, 2017	Oct. 17, 2017
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 822,900,000	$ 362,600,000
Distributions received	301,700,000	198,300,000	$ 158,000,000.0
Income from equity method investments	234,900,000	186,600,000	138,100,000
Impact of Change in Accounting Policy	(6,900,000)
Purchase price adjustment	0	300,000	0
Amberjack
Schedule of Equity Method Investments [Line Items]
Equity method investments	457,500,000	0
Distributions received	104,400,000	0	0
Income from equity method investments	80,300,000	0	0
Impact of Change in Accounting Policy	0
Purchase price adjustment		$ 0
Ownership interest (in percentage)		0.00%
Mars
Schedule of Equity Method Investments [Line Items]
Equity method investments	168,900,000	$ 187,400,000
Distributions received	119,300,000	125,900,000	88,300,000
Income from equity method investments	107,700,000	121,800,000	79,800,000
Impact of Change in Accounting Policy	$ (6,900,000)
Purchase price adjustment		$ 0
Ownership interest (in percentage)	71.50%	71.50%
Bengal
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 81,500,000	$ 79,700,000
Distributions received	19,000,000.0	19,000,000.0	19,600,000
Income from equity method investments	20,800,000	22,600,000	20,200,000
Impact of Change in Accounting Policy	$ 0
Purchase price adjustment		$ 0
Ownership interest (in percentage)	50.00%	50.00%
Poseidon
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 0	$ 2,300,000
Investment, excess distribution	24,400,000
Distributions received	33,100,000	38,400,000	41,900,000
Income from equity method investments	6,400,000	27,400,000	29,700,000
Impact of Change in Accounting Policy	$ 0
Purchase price adjustment		$ 0
Ownership interest (in percentage)	36.00%	36.00%
Other
Schedule of Equity Method Investments [Line Items]
Distributions received	$ 25,900,000	$ 15,000,000.0	8,200,000
Income from equity method investments	19,700,000	14,800,000	$ 8,400,000
Impact of Change in Accounting Policy	0
Purchase price adjustment		300,000
Permian Basin
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 72,200,000	$ 49,400,000
Ownership interest (in percentage)	50.00%	50.00%
LOCAP
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 8,200,000	$ 6,900,000
Ownership interest (in percentage)	41.48%	41.48%
Proteus
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 16,300,000	$ 17,400,000
Ownership interest (in percentage)	10.00%	10.00%
Endymion
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 18,300,000	$ 19,500,000
Ownership interest (in percentage)	10.00%	10.00%
Proteus and Endymion
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	$ 100,000
Permian Basin
Schedule of Equity Method Investments [Line Items]
Voting interest acquired					50.00%
LOCAP
Schedule of Equity Method Investments [Line Items]
Voting interest acquired				41.48%