Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Affiliates	$ 106,027			$ 100,188			$ 311,755	$ 295,629
Third Parties	29,868			25,596			89,388	77,799
Revenues	135,895			125,784			401,143	373,428
Operating costs and expenses:
Operations (exclusive of depreciation and amortization)	44,924			35,996			123,045	106,731
Depreciation and amortization	24,121			24,367			72,192	74,117
General and administrative	2,714			2,498			7,322	8,293
Total operating costs and expenses	71,759			62,861			202,559	189,141
Operating income	64,136			62,923			198,584	184,287
Other income (expense):
Equity in earnings of equity method investments	1,334			1,114			5,217	4,127
Interest expense	(18,807)			(18,042)			(57,059)	(53,249)
Interest income	2,243			540			3,322	1,581
Sales-type Lease, Selling Profit (Loss)	35,166			0			35,166	0
Gain (loss) on sale of assets and other	142			38			(57)	71
Total other income (expense)	20,078			(16,350)			(13,411)	(47,470)
Income before income taxes	84,214			46,573			185,173	136,817
State income tax benefit (expense)	(30)			(39)			(36)	(149)
Net Income	84,184	$ 47,159	$ 53,794	46,534	$ 41,499	$ 48,635	185,137	136,668
Allocation of net income attributable to noncontrolling interests	(1,839)			(1,531)			(5,920)	(5,354)
Net income attributable to the partners	$ 82,345			$ 45,003			$ 179,217	$ 131,314
Limited partners’ per unit interest in earnings—basic and diluted (in dollars per share)	$ 0.78			$ 0.43			$ 1.70	$ 1.25
Weighted average limited partners’ units outstanding (in shares)	105,440			105,440			105,440	104,908