Proposed Acquisition of Inotera (Details) TWD / shares in Units, $ / shares in Units, $ in Millions, TWD in Billions		6 Months Ended
		Nov. 30, 2016 USD ($) $ / shares	Nov. 30, 2016 TWD	Nov. 30, 2016 TWD / shares	Jun. 02, 2016 TWD / $	Sep. 03, 2015
Inotera [Member]
Proposed Acquisition of Inotera [Abstract]
Current Equity Ownership Percentage (in hundredths)	[1]				33.00%	33.00%
Percentage interest held by a third party (in hundredths)					67.00%
Inotera [Member] | Nanya and certain of its affiliates [Member]
Proposed Acquisition of Inotera [Abstract]
Percentage interest held by a third party (in hundredths)					32.00%
Inotera [Member]
Proposed Acquisition of Inotera [Abstract]
Foreign Currency Exchange Rate, Translation | TWD / $					32.6
Inotera [Member] | Scenario, Forecast [Member]
Proposed Acquisition of Inotera [Abstract]
Inotera Acquisition, Share Price | (per share)		$ 0.92		TWD 30
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Aggregate consideration payable for Inotera shares not already owned | $		$ 4,100
Inotera [Member] | Scenario, Forecast [Member] | 2021 Convertible Notes [Member] | Convertible notes [Member]
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Stated Interest Rate on Potential Convertible Debt issuable to Nanya		2.00%		2.00%
Inotera [Member] | Scenario, Forecast [Member] | Private Placement [Member]
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Trading-day period used to derive average share value of equity interests issuable to Nanya		30 days	30 days
Number of days prior to the optional share issuance to Nanya that pricing is established		30 days	30 days
Inotera [Member] | Scenario, Forecast [Member] | Maximum [Member] | 2021 Convertible Notes [Member] | Convertible notes [Member]
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Value of convertible debt available to be issued to Nanya in lieu of equity		$ 386	TWD 12.6
Inotera [Member] | Scenario, Forecast [Member] | Maximum [Member] | Private Placement [Member]
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Value of equity interests issuable to Nanya at our option as consideration for Inotera shares not already owned		964	31.5
Inotera [Member] | Scenario, Forecast [Member] | Minimum [Member]
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Debt planned to be incurred toward consideration for Inotera shares not already owned		2,500	80.0
Inotera [Member] | Scenario, Forecast [Member] | Minimum [Member] | Private Placement [Member]
Proposed Acquisition of Inotera, Potential Consideration [Abstract]
Value of equity interests issuable to Nanya at our option as consideration for Inotera shares not already owned		$ 193	TWD 6.3
Minimum price per share of equity interests issuable to Nanya | $ / shares		$ 10.00

[1] Entity is a variable interest entity.