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Investments - Additional Information (Detail) (Maximum [Member])	3 Months Ended
	Mar. 31, 2015
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities maturity period or average life	3 years
Average duration of portfolio	1 year

X

- Definition

Investment Securities Maturity Period

+ References

No definition available.

+ Details

Name:	mksi_InvestmentSecuritiesMaturityPeriod
Namespace Prefix:	mksi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Weighted Average Duration Investment Securities Portfolio

+ References

No definition available.

+ Details

Name:	mksi_WeightedAverageDurationInvestmentSecuritiesPortfolio
Namespace Prefix:	mksi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration