Debt - Senior Credit Facilities Narrative (Details) ¥ in Millions, $ in Millions				1 Months Ended			3 Months Ended		9 Months Ended			12 Months Ended
	Nov. 03, 2025 USD ($)	Oct. 29, 2025 USD ($)	Feb. 12, 2025	Nov. 30, 2024 USD ($)	Jan. 31, 2023 CNY (¥)	Mar. 31, 2022 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 CNY (¥)	Sep. 30, 2025 USD ($)	Sep. 30, 2025 CNY (¥)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Aug. 11, 2025 USD ($)	Mar. 06, 2025 CNY (¥)	Dec. 31, 2024 CNY (¥)	Jun. 30, 2024 CNY (¥)	Apr. 30, 2024 CNY (¥)	Dec. 31, 2023 CNY (¥)
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage									100.00%	100.00%
Proceeds from short-term borrowings									$ 606		$ 160
Repayments of Short-term Debt									555		418
Proceeds from Issuance of Long-Term Debt									2,926		299
Repayments of long-term debt									3,060		$ 1,019
5 Year Delayed-Draw Term Loan | Term Loan Facility
Debt Instrument [Line Items]
Debt instrument, term						5 years
Debt instrument, face amount						$ 1,000
Proceeds from Issuance of Long-Term Debt									$ 330
5 Year Delayed-Draw Term Loan | Term Loan Facility | Subsequent Event
Debt Instrument [Line Items]
Repayments of long-term debt	$ 50	$ 150
January 2023 CSIT One Year Working Capital Term Loan | January 2023 CSIT One Year Working Capital Term Loan
Debt Instrument [Line Items]
Debt instrument, term					12 months
Debt instrument, face amount | ¥					¥ 800
Repayments of Debt | ¥								¥ 800
January 2023 CSIT One Year Working Capital Term Loan | January 2023 CSIT One Year Working Capital Term Loan | Variable Interbank Interest Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate					0.50%
June 2024 CNC Three Year Working Capital Loan | June 2024 CNC Three Year Working Capital Loan
Debt Instrument [Line Items]
Debt instrument, face amount | ¥																¥ 800
Debt Instrument, Interest Rate, Stated Percentage																2.75%
Proceeds from Issuance of Long-Term Debt | ¥										¥ 720
Secured Debt | Amended restated receivable purchasing facility
Debt Instrument [Line Items]
Percentage of fair value of sales receivables									100.00%	100.00%
Transfer of financial assets accounted for as sales, amount derecognized									$ 1,200			$ 1,500
Proceeds collected on accounts receivable sold under factoring facilities									1,200			1,500
Trade Receivables Pledged As Collateral									$ 78
Europe Factoring Agreements
Debt Instrument [Line Items]
Transfer of financial assets accounted for as sales, non-recourse basis, account receivable percentage									100.00%
Japan Factoring Agreements
Debt Instrument [Line Items]
Transfer of financial assets accounted for as sales, non-recourse basis, account receivable percentage									100.00%
Singapore Factoring Agreements
Debt Instrument [Line Items]
Transfer of financial assets accounted for as sales, non-recourse basis, account receivable percentage									90.00%
China Factoring Agreements
Debt Instrument [Line Items]
Transfer of financial assets accounted for as sales, non-recourse basis, account receivable percentage									100.00%
China, Europe, Japan and Singapore Factoring Agreements
Debt Instrument [Line Items]
Transfer of financial assets accounted for as sales, amount derecognized									$ 546			700
Proceeds collected on accounts receivable sold under factoring facilities									533			640
Master Discounting Agreement
Debt Instrument [Line Items]
Transfer of financial assets accounted for as sales, amount derecognized									53			$ 100
November 2024 US Term Loan | Term Loan Facility
Debt Instrument [Line Items]
Debt instrument, term				364 days
Debt instrument, face amount				$ 1,000
Proceeds from short-term borrowings							$ 500
Repayments of Short-term Debt									500
November 2024 US Term Loan | Term Loan Facility | Minimum | Term SOFR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.30%
November 2024 US Term Loan | Term Loan Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				0.30%
November 2024 US Term Loan | Term Loan Facility | Maximum | Term SOFR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				2.25%
November 2024 US Term Loan | Term Loan Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.25%
March 2025 CNC Three Year Working Capital Loan | March 2025 CNC Three Year Working Capital Loan
Debt Instrument [Line Items]
Debt instrument, face amount | ¥														¥ 750
Proceeds from Issuance of Long-Term Debt | ¥										¥ 560
U.S. Credit Agreements | Minimum
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)			0.25%
U.S. Credit Agreements | Maximum
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)			0.30%
Various senior notes | Maximum
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)			0.50%
December 2024 CNC Three Year Working Capital Loan | December 2024 CNC Three Year Working Capital Loan
Debt Instrument [Line Items]
Debt instrument, face amount | ¥															¥ 1,000
Proceeds from Issuance of Long-Term Debt | ¥										¥ 872
Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity													$ 1,750
Available for borrowing									$ 1,750
Revolving Credit Facility | Revolving Credit Facility | Minimum | Variable Interbank Interest Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate									1.00%	1.00%
Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate									0.00%	0.00%
Revolving Credit Facility | Revolving Credit Facility | Maximum | Variable Interbank Interest Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate									2.00%	2.00%
Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate									1.00%	1.00%
Revolving Credit Facility | China Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity | ¥					¥ 1,750										¥ 550		¥ 750
Available for borrowing									$ 54
December 2023 CNC Three Year Working Capital Loan | December 2023 CNC Three Year Working Capital Loan
Debt Instrument [Line Items]
Debt instrument, face amount | ¥																		¥ 800
Debt Instrument, Interest Rate, Stated Percentage																		2.80%