Debt - Schedule of China Credit Facilities (Details) ¥ in Millions, $ in Millions				1 Months Ended
		Mar. 26, 2026 CNY (¥)	Mar. 10, 2026 CNY (¥)	Apr. 30, 2025 CNY (¥)	Mar. 31, 2026 USD ($)	Mar. 31, 2026 CNY (¥)
China Credit Facilities
Debt Instrument [Line Items]
Revolving credit facilities(2)					$ 628	¥ 4,332
China Credit Facilities | CSIT Revolving Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[1]					¥ 550
Debt Instrument, Interest Rate, Stated Percentage					2.70%	2.70%
Revolving credit facilities(2)					$ 0	¥ 0
China Credit Facilities | CNCC Working Capital Loan Agreement Due December 25, 2026 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 800
Debt Instrument, Interest Rate, Stated Percentage					2.34%	2.34%
Revolving credit facilities(2)					$ 116	¥ 800
China Credit Facilities | CNCC Working Capital Loan Agreement Due June 17, 2027 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 200
Debt Instrument, Interest Rate, Stated Percentage					2.34%	2.34%
Revolving credit facilities(2)					$ 25	¥ 170
China Credit Facilities | CNCC Working Capital Loan Agreement Due June 28, 2027 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 800
Debt Instrument, Interest Rate, Stated Percentage					2.34%	2.34%
Revolving credit facilities(2)					$ 99	¥ 680
China Credit Facilities | CNCC Working Capital Loan Agreement Due December 21, 2027 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[3]					¥ 500
Debt Instrument, Interest Rate, Stated Percentage					2.44%	2.44%
Revolving credit facilities(2)					$ 65	¥ 450
China Credit Facilities | CNCC Working Capital Loan Agreement Due March 6, 2028 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 750
Debt Instrument, Interest Rate, Stated Percentage					2.34%	2.34%
Revolving credit facilities(2)					$ 98	¥ 675
China Credit Facilities | CNCC Working Capital Loan Agreement Due June 9, 2028 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 1,000
Debt Instrument, Interest Rate, Stated Percentage					2.35%	2.35%
Revolving credit facilities(2)					$ 126	¥ 872
China Credit Facilities | CNCC Working Capital Loan Agreement Due July 3, 2028 [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 300
Debt Instrument, Interest Rate, Stated Percentage					2.34%	2.34%
Revolving credit facilities(2)					$ 41	¥ 285
China Credit Facilities | CNCC Working Capital Loan Agreement Due October 20, 2028
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	[2]					¥ 300
Debt Instrument, Interest Rate, Stated Percentage					2.34%	2.34%
Revolving credit facilities(2)					$ 43	¥ 300
China Credit Facilities | CNCC Term Loan Agreement Due March 11, 2031
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			¥ 600			¥ 600	[4]
Debt Instrument, Interest Rate, Stated Percentage					2.41%	2.41%
Revolving credit facilities(2)					$ 15	¥ 100
Debt instrument, term			7 years
China Credit Facilities | CNCC CNY950M Term Loan Agreement
Debt Instrument [Line Items]
Debt instrument, term		5 years
China Revolving Credit Facility | CNCC Revolving Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				¥ 100
Debt instrument, term				12 months
China Revolving Credit Facility | CNCC CNY950M Term Loan Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		¥ 950

[1] Revolving credit facility guaranteed by Celanese U.S. (the "CSIT Revolving Credit Facility"), which bears interest at a fixed rate. The CSIT Revolving Credit Facility was fully repaid on January 13, 2026.

[2] Senior unsecured working capital loan bearing interest at certain floating interest rates.

[3] Senior unsecured working capital loan bearing interest at a fixed interest rate.

[4] On March 10, 2026, CNCC entered into a CNY600 million senior unsecured term loan credit agreement bearing interest at certain floating interest rates, expiring seven years from the drawdown date.