Significant Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2019

Statement [Line Items]

Key Management Personnel Compensation

c. Key management personnel compensation

	For the years ended December 31,
	2017		2018		2019
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Short-term employee benefits	$	271,554	$	387,294	$	271,135
Post-employment benefits		3,478		4,660		2,406
Termination benefits		6,957		—		3,415
Share-based payment		68		293,857		62,203
Others		294		435		578
Total	$	282,351	$	686,246	$	339,737

Subsidiaries [member]

Statement [Line Items]

Significant Transactions Between the Company and Related Parties

a. Significant intercompany transactions between consolidated entities were as follows:

For the year ended December 31, 2017

Entity	Counterparty	Transactions (Note A)
		Account	Amount			Terms (Note B)
			NT$
			(In Thousands)
UMC	UMC-USA	Sales	$	59,968,172		Net 60 days
UMC	UMC-USA	Accounts receivable		6,737,723		—
UMC	UMC GROUP JAPAN	Sales		4,212,523		Net 60 days
UMC	UMC GROUP JAPAN	Accounts receivable		659,488		—
UMC	USCXM	Sales		998,899 (Note C	)	Net 30 days
UMC	USCXM	Accounts receivable		4,790,930		—
UMC	USCXM	Loan receivable		3,924,360		—
HJ	UMC-USA	Sales		214,147		Net 60 days
HJ	UMC-USA	Accounts receivable		35,498		—
HJ	UMC GROUP JAPAN	Sales		223,740		Net 60 days
HJ	UMC GROUP JAPAN	Accounts receivable		43,332		—
USCXM	UMC-USA	Sales		241,220		Net 60 days
USCXM	UMC-USA	Accounts receivable		141,272		—

For the year ended December 31, 2018

Entity	Counterparty	Transactions (Note A)
		Account	Amount			Terms (Note B)
			NT$
			(In Thousands)
UMC	UMC-USA	Sales	$	57,107,585		Net 60 days
UMC	UMC-USA	Accounts receivable		7,312,272		—
UMC	UMC GROUP JAPAN	Sales		4,159,637		Net 60 days
UMC	UMC GROUP JAPAN	Accounts receivable		905,048		—
UMC	USCXM	Sales		1,356,567 (Note C	)	Net 30 days
UMC	USCXM	Accounts receivable		48,163		—
USCXM	UMC-USA	Sales		698,988		Net 60 days
USCXM	UMC-USA	Accounts receivable		120,678		—
HJ	UMC-USA	Sales		307,471		Net 60 days
HJ	UMC-USA	Accounts receivable		35,161		—
HJ	UMC GROUP JAPAN	Sales		272,218		Net 60 days
HJ	UMC GROUP JAPAN	Accounts receivable		61,971		—

For the year ended December 31, 2019

Entity	Counterparty	Transactions (Note A)
		Account	Amount			Terms (Note B)
			NT$
			(In Thousands)
UMC	UMC-USA	Sales	$	47,736,335		Net 60 days
UMC	UMC-USA	Accounts receivable		5,937,706		—
UMC	UMC GROUP JAPAN	Sales		3,933,964		Net 60 days
UMC	UMC GROUP JAPAN	Accounts receivable		608,622		—
UMC	USCXM	Sales		1,209,310 (Note C	)	Net 30 days
UMC	USCXM	Accounts receivable		31,334		—
UMC	USCXM	Loan receivable		1,201,200		—
USCXM	UMC-USA	Sales		745,226		Net 60 days
USCXM	UMC-USA	Accounts receivable		33,242		—
HJ	UMC-USA	Sales		152,012		Net 60 days
HJ	UMC-USA	Accounts receivable		21,138		—
HJ	UMC GROUP JAPAN	Sales		250,736		Net 60 days
HJ	UMC GROUP JAPAN	Accounts receivable		51,150		—

Note A: The significant intercompany transactions listed above include downstream transactions.

Note B: The sales price to the above related parties was determined through mutual agreement in reference to market conditions.

Note C: UMC authorized technology licenses to its subsidiary, USCXM, in the amount of US$0.35 billion, which was recognized as deferred revenue to be realized over time.

Other related parties [member]

Statement [Line Items]

Significant Transactions Between the Company and Related Parties

(ii) Operating revenues

	For the years ended December 31,
	2017		2018		2019
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Associates	$	1,357,720	$	1,291,398	$	1,532,339
Joint ventures		12,465		4,277		—
Others		30,417		27,881		45,523
Total	$	1,400,602	$	1,323,556	$	1,577,862

(iii) Accounts receivable, net

	As of December 31,
	2018		2019
	NT$		NT$
	(In Thousands)		(In Thousands)
Associates	$	134,646	$	278,702
Others		4,266		11,243
Total	$	138,912	$	289,945

The sales price to the above related parties was determined through mutual agreement in reference to market conditions. The collection period for domestic sales to related parties was month-end 30~60 days, while the collection period for overseas sales was net 30~60 days.

(iv) Refund liabilities (classified under other current liabilities)

	As of December 31,
	2018		2019
	NT$		NT$
	(In Thousands)		(In Thousands)
Associates	$	1,287	$	7,880
Others		71		48
Total	$	1,358	$	7,928

(v) Significant asset transactions

Acquisition of financial assets at fair value through profit or loss – noncurrent

For the years ended December 31, 2017 and 2018: None.

					For the year ended December 31, 2019
	Trading Volume (In thousands of shares)		Transaction underlying		Purchase price
					NT$
					(In Thousands)
Associates		500		Stock of MATERIALS ANALYSIS TECHNOLOGY INC.	$	32,923
Associates		1,900		Stock of GEAR RADIO LTD.		37,211
Total					$	70,134

Acquisition of investments accounted for under the equity method

For the year ended December 31, 2017: None.

				For the year ended December 31, 2018
	Trading Volume (In thousands of shares)		Transaction underlying	Purchase price
				NT$
				(In Thousands)
Associates		84,000	Stock	$	840,000

				For the year ended December 31, 2019
	Trading Volume (In thousands of shares)		Transaction underlying	Purchase price
				NT$
				(In Thousands)
Associates		72,000	Stock	$	720,000

Acquisition of intangible assets

	Purchase price
	For the years ended December 31,
	2017		2018		2019
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Associates	$	322,808	$	200,610	$	339,463

Disposal of subsidiary

For the years ended December 31, 2017 and 2019: None.

				For the year ended December 31, 2018
	Trading Volume (In thousands of shares)		Transaction underlying	Proceeds		Disposal (loss) gain
				NT$		NT$
				(In Thousands)		(In Thousands)
Others		46,168	Stock of UNISTARS CORPORATION	$	4,617	$	(31,856	)

Disposal of financial assets

				For the year ended December 31, 2017
	Trading Volume (In thousands of shares)		Transaction underlying	Proceeds		Disposal (loss) gain
				NT$		NT$
				(In Thousands)		(In Thousands)
Others		6,489	Stock of ASIA PACIFIC MICROSYSTEMS, INC.	$	50,745	$	(13,753	)

For the years ended December 31, 2018 and 2019: None.

(vi) Others

Mask expenditure

	For the years ended December 31,
	2017		2018		2019
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Others	$	994,710	$	1,750,088	$	2,346,263

Other payables of mask expenditure

	As of December 31,
	2017		2018		2019
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Others	$	580,789	$	571,036	$	683,892