Cash and Cash Equivalents (Tables)

12 Months Ended

Dec. 31, 2018

Cash And Cash Equivalents [Abstract]

Summary of Cash and Cash Equivalents

	December 31
	2017		2018
	NT$		NT$
	(In Millions)
Cash
Cash on hand	$	383	$	463
Bank deposits		7,877		10,575
		8,260		11,038
Cash equivalents (investments with maturities of less    than three months)
Commercial paper	$	10,179	$	6,144
Negotiable certificate of deposit		7,950		7,600
Time deposits		2,436		2,863
		20,565		16,607
	$	28,825	$	27,645

Annual Yield Rates of Bank Deposits, Commercial Paper, Negotiable Certificates of Deposit and Time Deposits

The annual yield rates of bank deposits, commercial paper, negotiable certificates of deposit and time deposits as of balance sheet dates were as follows:

	December 31
	2017	2018
Bank deposits	0.00%-0.70%	0.00%-0.50%
Commercial paper	0.32%-0.40%	0.47%-0.57%
Negotiable certificate of deposit	0.40%-0.50%	0.55%-0.60%
Time deposits	0.52%-4.40%	0.09%-4.40%