Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 1,844	$ 1,313
Accounts receivable, net	1,549	1,214
Inventories	965	918
Prepaid expenses and other current assets	87	32
Total current assets	4,445	3,477
Property, plant and equipment, net	6,919	6,920
Operating lease right-of-use assets	452	461
Goodwill	1,085	1,083
Customer relationships, net	399	444
Other intangible assets, net	154	168
Equity method investments	1,009	1,059
Other assets, net	256	223
Total assets	14,719	13,835
Current liabilities
Accounts payable	667	536
Accrued and other liabilities	818	821
Total current liabilities	1,485	1,357
Long-term debt, net	3,555	3,566
Deferred income taxes	1,396	1,368
Pension and other post-retirement benefits	373	391
Operating lease liabilities	369	376
Other liabilities	202	199
Total liabilities	7,380	7,257
Commitments and contingencies (Note 13)
Stockholders' equity
Preferred stock, $0.01 par value, 50,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.01 par value, 300,000,000 shares authorized; 134,651,380 and 134,651,380 shares issued at June 30, 2021 and December 31, 2020, respectively	1	1
Common stock, held in treasury, at cost; 6,501,665 and 6,821,174 shares at June 30, 2021 and December 31, 2020, respectively	(378)	(401)
Additional paid-in capital	571	569
Retained earnings	6,633	5,938
Accumulated other comprehensive loss	(56)	(64)
Total Westlake Chemical Corporation stockholders' equity	6,771	6,043
Noncontrolling interests	568	535
Total equity	7,339	6,578
Total liabilities and equity	$ 14,719	$ 13,835
Preferred stock, par value, in dollars per share	$ 0.01	$ 0.01
Common stock, par value, in dollars per share	$ 0.01	$ 0.01
Preferred stock, shares outstanding	0	0
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, shares authorized	300,000,000	300,000,000
Common Stock [Member]
Stockholders' equity
Total equity	$ 1	$ 1
Common Stock, Shares, Issued	134,651,380	134,651,380
Common Stock, Held in Treasury [Member]
Stockholders' equity
Total equity	$ (378)	$ (401)
Treasury Stock, Shares	6,501,665	6,821,174