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Actuarial Assumptions to Determine Benefit Obligations (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Taiwan
Weighted-average assumptions used to determine benefit obligations:
Discount rate	1.50%	1.75%	2.00%
Rate of compensation increase	4.25%	4.25%	4.25%
Weighted-average assumptions used to determine net projected benefit cost:
Discount rate	1.50%	1.75%	2.00%
Expected long-term return on plan assets	2.00%	2.00%	2.00%
Rate of compensation increase	4.25%	4.25%	4.25%
Korea
Weighted-average assumptions used to determine benefit obligations:
Discount rate	3.80%	3.90%	4.10%
Rate of compensation increase	3.50%	4.00%	5.00%
Weighted-average assumptions used to determine net projected benefit cost:
Discount rate	3.80%	3.90%	4.10%
Expected long-term return on plan assets	1.10%	1.20%	2.00%
Rate of compensation increase	3.50%	4.00%	5.00%

X

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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X

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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The interest rate used to adjust for the time value of money.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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X

- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

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-Section 50
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- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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