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Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Parenthetical) (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Not included in cash and cash equivalent amount $ 95,212us-gaap_CashAndCashEquivalentsFairValueDisclosure $ 167,517us-gaap_CashAndCashEquivalentsFairValueDisclosure
Non Negotiable Time Deposits [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Not included in cash and cash equivalent amount $ 9,612us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= mksi_NonNegotiableTimeDepositsMember
$ 7,997us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= mksi_NonNegotiableTimeDepositsMember