Members' Equity - Computation and Distribution Activity (Details) - USD ($)			3 Months Ended												12 Months Ended
	Feb. 22, 2019	Jan. 25, 2019	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	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, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stock repurchase program, authorized amount																		$ 100,000,000
Common units repurchased (in shares)															383,614
Common units repurchased															$ 1,200,000	$ 0	$ 0
Business acquisition, equity interest issued or issuable, number of shares (in shares)		304,822,035
Sale of stock, maximum amount allowed to be sold through agent	$ 400,000,000.0
Distributed earnings allocated to:
Total distributed earnings															186,600,000	484,700,000	197,700,000
Undistributed income (loss) allocated to:
Total undistributed loss															(608,100,000)	(1,604,000,000.0)	(210,900,000)
Net loss allocated to:
Total net loss															$ (421,500,000)	$ (1,119,300,000)	$ (13,200,000)
Basic and diluted net loss per unit:
Basic (in dollars per share)			$ (0.31)	$ 0.03	$ 0.01	$ (0.59)	$ (1.92)	$ 0.02	$ (0.03)	$ (0.45)	$ (0.34)	$ 0.04	$ 0.15	$ 0.07	$ (0.86)	$ (2.41)	$ (0.07)
Diluted (in dollars per share)			(0.31)	0.03	0.01	(0.59)	(1.92)	0.02	(0.03)	(0.45)	(0.34)	0.04	0.15	0.07	$ (0.86)	$ (2.41)	$ (0.07)
Weighted average common units outstanding (in shares)															489,300,000	463,900,000	181,100,000
Distribution declared/unit (in dollars per share)			$ 0.09375	$ 0.09375	$ 0.09375	$ 0.09375	$ 0.1875	$ 0.283	$ 0.283	$ 0.279	$ 0.275	$ 0.271	$ 0.267	$ 0.263
Unvested restricted units
Distributed earnings allocated to:
Total distributed earnings															$ 3,100,000	$ 5,700,000	$ 2,800,000
Undistributed income (loss) allocated to:
Total undistributed loss															(9,700,000)	(19,200,000)	(3,000,000.0)
Net loss allocated to:
Total net loss															(6,600,000)	(13,500,000)	(200,000)
Common Unit
Distributed earnings allocated to:
Total distributed earnings															183,500,000	479,000,000.0	194,900,000
Undistributed income (loss) allocated to:
Total undistributed loss															(598,400,000)	(1,584,800,000)	(207,900,000)
Net loss allocated to:
Total net loss															$ (414,900,000)	$ (1,105,800,000)	$ (13,000,000.0)