Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities
Net income	$ 369,159	$ 334,626	$ 334,829
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	111,899	110,203	121,074
Loss from disposition of property, plant and equipment	2,345	4,933	4,707
Other losses (gains), net	(182)	(27)	356
Changes in operating assets and liabilities
Accounts receivable—third parties	7,221	1,332	(14,435)
Net accounts receivable—Westlake	25,737	27,331	74,197
Inventories	374	283	4,183
Prepaid expenses and other current assets	(2)	(137)	91
Accounts payable—third parties	(2,693)	1,569	(17,001)
Accrued and other liabilities	(5,821)	4,026	(37,533)
Other, net	(23,036)	(32,140)	(6,732)
Net cash provided by operating activities	485,001	451,999	463,736
Cash flows from investing activities
Additions to property, plant and equipment	(48,971)	(46,821)	(54,118)
Investments with Westlake under the Investment Management Agreement	(40,000)	(174,116)	(319,884)
Maturities of investments with Westlake under the Investment Management Agreement	0	145,000	362,000
Net cash used for investing activities	(88,971)	(75,937)	(12,002)
Cash flows from financing activities
Proceeds from debt payable to Westlake	219,000	209,250	32,000
Repayment of debt payable to Westlake	(219,000)	(209,250)	(32,000)
Distributions to noncontrolling interest retained in OpCo by Westlake	(329,898)	(315,805)	(337,598)
Distributions to unitholders	(66,435)	(66,420)	(66,411)
Net cash used for financing activities	(396,333)	(382,225)	(404,009)
Net increase (decrease) in cash and cash equivalents	(303)	(6,163)	47,725
Cash and cash equivalents at beginning of the year	58,619	64,782	17,057
Cash and cash equivalents at end of the year	$ 58,316	$ 58,619	$ 64,782