Earnings Per Unit - Computation of Basic and Diluted Earnings per Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share Basic [Line Items]
Net income (loss)	$ 70,247	$ 60,775	$ 174,351	$ 131,422
Net (income) loss attributable to noncontrolling interests	0	(22)	0	(1)
Distributions on Series A redeemable preferred units	0	0	0	(25)
Distributions on Series B cumulative convertible preferred units	(5,250)	(5,250)	(15,750)	(15,750)
NET INCOME (LOSS) ATTRIBUTABLE TO THE GENERAL PARTNER AND COMMON AND SUBORDINATED UNITS	64,997	55,503	158,601	115,646
ALLOCATION OF NET INCOME (LOSS):
General partner interest	0	0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO THE GENERAL PARTNER AND COMMON AND SUBORDINATED UNITS	64,997	$ 55,503	$ 158,601	$ 115,646
NET INCOME (LOSS) ATTRIBUTABLE TO LIMITED PARTNERS PER COMMON AND SUBORDINATED UNIT:
Effect of dilutive securities (in shares)		0	0	0
Common Units
ALLOCATION OF NET INCOME (LOSS):
Allocation of net income (loss)	$ 64,997	$ 29,188	$ 134,608	$ 71,037
NET INCOME (LOSS) ATTRIBUTABLE TO LIMITED PARTNERS PER COMMON AND SUBORDINATED UNIT:
Weighted average units outstanding (basic) (in shares)	205,957	106,706	155,513	105,254
Effect of dilutive securities (in shares)	0	0	0	0
Weighted average units outstanding (diluted) (in shares)	205,957	106,706	155,513	105,254
Per unit (basic) (in dollars per share)	$ 0.32	$ 0.27	$ 0.87	$ 0.67
Per unit (diluted) (in dollars per share)	$ 0.32	$ 0.27	$ 0.87	$ 0.67
Subordinated Units
ALLOCATION OF NET INCOME (LOSS):
Allocation of net income (loss)	$ 0	$ 26,315	$ 23,993	$ 44,609
NET INCOME (LOSS) ATTRIBUTABLE TO LIMITED PARTNERS PER COMMON AND SUBORDINATED UNIT:
Weighted average units outstanding (basic) (in shares)	0	96,329	50,458	96,021
Effect of dilutive securities (in shares)	0	0	0	0
Weighted average units outstanding (diluted) (in shares)	0	96,329	50,458	96,021
Per unit (basic) (in dollars per share)	$ 0	$ 0.27	$ 0.48	$ 0.46
Per unit (diluted) (in dollars per share)	$ 0	$ 0.27	$ 0.48	$ 0.46