Condensed Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities
Net income (loss)	$ 599.4	$ (200.1)
Adjustments to reconcile net income (loss) to net cash and cash equivalents provided by (used for) operating activities:
Stock-based compensation	1.3	4.1
Loss on debt extinguishment	38.9	0.0
Depreciation and amortization	287.2	283.0
Deferred income taxes	(26.8)	(52.1)
Qualified pension plan contributions	(0.6)	(1.2)
Qualified pension plan income	(13.7)	(5.9)
Change in:
Receivables	(274.5)	64.1
Income taxes receivable/payable	(22.6)	(15.8)
Inventories	(67.6)	75.7
Other current assets	12.0	(18.3)
Accounts payable and accrued liabilities	143.6	(74.9)
Other assets	(2.5)	0.6
Other noncurrent liabilities	32.2	(5.6)
Other operating activities	1.3	1.8
Net operating activities	707.6	55.4
Investing Activities
Capital expenditures	(86.4)	(166.5)
Payments under ethylene long-term supply contracts	0.0	461.0
Payments under other long-term supply contracts	0.0	75.8
Net investing activities	(86.4)	(703.3)
Long-term debt:
Borrowings	365.0	1,163.2
Repayments	(855.2)	(425.8)
Debt early redemption premiums	(31.0)	0.0
Stock options exercised	50.2	0.5
Dividends paid	(63.7)	(63.1)
Debt issuance costs	(3.1)	(9.6)
Net financing activities	(537.8)	665.2
Effect of exchange rate changes on cash and cash equivalents	(0.3)	(0.3)
Net increase in cash and cash equivalents	83.1	17.0
Cash and cash equivalents, beginning of year	189.7	220.9
Cash and cash equivalents, end of period	272.8	237.9
Cash paid for interest and income taxes:
Interest, net	153.5	122.3
Income taxes, net of refunds	82.6	3.1
Non-cash investing activities:
Decrease in capital expenditures included in accounts payable and accrued liabilities	$ 26.1	$ 38.6