Earnings Per Unit - Computation of Basic and Diluted Earnings per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share Basic [Line Items]
NET INCOME (LOSS)	$ 40,017	$ 70,247	$ 95,087	$ 9,017	$ 164,138	$ 60,775	$ 28,690	$ 41,957	$ 214,368	$ 295,560	$ 157,153
Net (income) loss attributable to noncontrolling interests									0	24	(34)
Distributions on Series A redeemable preferred units									0	(25)	(3,117)
Distributable preferred stock dividends									21,000	21,000	1,925
NET INCOME (LOSS) ATTRIBUTABLE TO THE GENERAL PARTNER AND COMMON AND SUBORDINATED UNITS SUBSEQUENT TO INITIAL PUBLIC OFFERING	34,767	64,997	89,837	3,767	158,865	55,503	23,488	36,655	193,368	274,511	152,145
Allocation of net loss subsequent to initial public offering attributable to:
General partner interest									0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO THE GENERAL PARTNER AND COMMON AND SUBORDINATED UNITS SUBSEQUENT TO INITIAL PUBLIC OFFERING	$ 34,767	$ 64,997	$ 89,837	$ 3,767	158,865	$ 55,503	$ 23,488	$ 36,655	193,368	274,511	152,145
Series B Cumulative Convertible Preferred Units
Net loss attributable to common and subordinated units per unit:
Distributions on preferred units					21,000					21,000
Series A Redeemable Preferred Units
Net loss attributable to common and subordinated units per unit:
Distributions on preferred units					$ 300					300
Common Units
Allocation of net loss subsequent to initial public offering attributable to:
Allocation of loss									$ 169,375	$ 154,662	$ 98,389
Net loss attributable to common and subordinated units per unit:
Weighted average units outstanding, basic (in shares)									168,230,000	106,064,000	97,400,000
Number of performance units award included in calculation of diluted EPU									146,000	15,200,000	0
Weighted average units outstanding, diluted (in shares)									168,376,000	121,264,000	97,400,000
Per unit (basic) (in usd per share)	$ 170	$ 320	$ 450	$ 20.00	$ 0.78	$ 0.27	$ 0.17	$ 0.23	$ 1.01	$ 1.46	$ 1.01
Per unit (diluted) (in usd per share)	170	320	440	20.00	0.72	0.27	0.17	0.23	$ 1.01	$ 1.45	$ 1.01
Subordinated Units
Allocation of net loss subsequent to initial public offering attributable to:
Allocation of loss									$ 23,993	$ 119,849	$ 53,756
Net loss attributable to common and subordinated units per unit:
Weighted average units outstanding, basic (in shares)									37,740,000	96,099,000	95,149,000
Number of performance units award included in calculation of diluted EPU									0	247,000	0
Weighted average units outstanding, diluted (in shares)									37,740,000	96,346,000	95,149,000
Per unit (basic) (in usd per share)	0	0	390	20.00	0.78	0.27	0.06	0.13	$ 0.64	$ 1.25	$ 0.56
Per unit (diluted) (in usd per share)	$ 0	$ 0	$ 390	$ 20.00	$ 0.78	$ 0.27	$ 0.06	$ 0.13	$ 0.64	$ 1.25	$ 0.56