Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net income	$ 265,995	$ 240,985
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	77,767	80,382
Loss from disposition of property, plant and equipment	1,000	458
Other gains, net	(522)	(819)
Changes in operating assets and liabilities
Accounts receivable—third parties	5,170	2,647
Net accounts receivable—Westlake	(10,136)	8,217
Inventories	832	(88)
Prepaid expenses and other current assets	(87)	(189)
Accounts payable	711	(662)
Accrued and other liabilities	1,398	4,869
Other, net	(1,252)	(646)
Cash flows from investing activities	340,876	335,154
Cash flows from investing activities
Additions to property, plant and equipment	(29,170)	(30,028)
Maturities of investments with Westlake under the Investment Management Agreement	276,000	405,445
Investments with Westlake under the Investment Management Agreement	(305,000)	(421,445)
Other	0	46
Net cash used for investing activities	(58,170)	(45,982)
Cash flows from financing activities
Net proceeds from private placement of common units	0	62,661
Proceeds from debt payable to Westlake	0	123,511
Repayment of debt payable to Westlake	0	(201,445)
Quarterly distributions to noncontrolling interest retained in OpCo by Westlake	(229,526)	(229,260)
Quarterly distributions to unitholders	(49,772)	(45,736)
Net cash used for financing activities	(279,298)	(290,269)
Net increase (decrease) in cash and cash equivalents	3,408	(1,097)
Cash and cash equivalents at beginning of period	19,923	19,744
Cash and cash equivalents at end of period	$ 23,331	$ 18,647