Consolidated Statement of Cash Flows - USD ($) $ in Thousands		3 Months Ended									6 Months Ended				9 Months Ended				12 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018		Jun. 30, 2019		Jun. 30, 2018		Sep. 30, 2019		Sep. 30, 2018		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Cash flows from operating activities(a):
Net income (loss)		$ 61,492	$ 57,607	$ 57,638		$ 57,303	$ 54,312	$ 52,470	$ 51,432		$ 115,245		$ 103,902		$ 176,737		$ 158,214		$ 236,677		$ 215,517		$ 175,049
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, amortization and accretion		51,881	51,626	51,580		51,707	51,684	52,083	52,054		103,206		104,137		155,087		155,821		207,396		207,528		207,764
Amortization of deferred financing costs				346					346		692		692		1,038		1,038		1,384		1,384		1,384
Asset write-down charges		0	185	190		249	0	0	344		375		344		375		344		1,050		593		181
Changes in assets and liabilities:
Increase (decrease) in accrued interest				9,622					9,622		0		0		9,622		9,622
Increase (decrease) in accounts payable				(32)					(171)		605		449		(3,844)		500		(3,102)		(81)		(1,110)
Increase (decrease) in other liabilities				5,968					6,107		9,473		6,020		15,477		10,826		18,780		15,648		779
Decrease (increase) in receivables				1,516					(163)		2,597		231		1,978		(158)		1,887		(1,745)		946
Decrease (increase) in other assets				3,675					(1,485)		14,277		9,155		14,256		12,505		(13,003)		(12,003)		9,574
Net cash provided by (used for) operating activities				123,153	[1]				121,056	[1]	217,916	[1]	206,620	[1]	342,214	[1]	323,702	[1]	451,069		426,841	[1]	394,567	[1]
Cash flows from investing activities(a):
Capital expenditures				18,678					14,766		41,358		32,300		64,204		51,995		(86,610)		(70,929)	[1]	(48,312)	[1]
Net cash provided by (used for) investing activities	[1]			(18,678)					(14,766)		(41,358)		(32,300)		(64,204)		(51,995)		(86,610)		(70,929)		(48,312)
Cash flows from financing activities(a):
Contribution (Distribution) from/to Member				(105,472)					(108,573)		(177,586)		(183,436)		(278,231)		(278,242)		(362,759)	[2]	(367,976)	[1],[2]	(335,034)	[1],[2]
Net cash provided by (used for) financing activities	[1]			(105,472)					(108,573)		(177,586)		(183,436)		(278,231)		(278,242)		(362,759)		(367,976)		(335,034)
Net increase (decrease) in cash and cash equivalents				(997)					(2,283)		(1,028)		(9,116)		(221)		(6,535)		1,700		(12,064)		11,221
Cash and cash equivalents at beginning of year		17,679	17,710	18,707		24,236	21,655	28,488	30,771		18,707		30,771		18,707		30,771		18,707		30,771		19,550
Cash and cash equivalents at end of year		$ 18,486	$ 17,679	$ 17,710		$ 18,707	$ 24,236	$ 21,655	$ 28,488		$ 17,679		$ 21,655		$ 18,486		$ 24,236		$ 20,407		$ 18,707		$ 30,771

[1] The Company receives no cash from, and is not party to, the CCIC transactions described in note 2. Such transactions, however, are reflected on the cash flow statement for GAAP purposes as if an amount equal to the lease component for such transactions had been received by the Company, and as such, the amounts have been recorded as fixed assets (in the form of permanent improvements) and deferred revenues.

[2] The Company receives no cash from, and is not party to, the CCIC transactions described in note 2.