Business Segment, Geographic Area, Product and Significant Customer Information - Schedule of Capital Expenditures, Depreciation and Amortization Expense and Segment Assets by Reportable Segment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Capital expenditures	$ 13,183	$ 12,410	$ 17,705
Depreciation and amortization	20,514us-gaap_DepreciationAndAmortization	17,102us-gaap_DepreciationAndAmortization	14,442us-gaap_DepreciationAndAmortization
Accounts receivable	106,362us-gaap_AccountsReceivableNetCurrent	116,744us-gaap_AccountsReceivableNetCurrent
Inventory	155,169us-gaap_InventoryNet	142,727us-gaap_InventoryNet
Total segment assets	261,531mksi_SegmentAssets	259,471mksi_SegmentAssets
Operating Segments [Member] \| Advanced Manufacturing Capital Equipment [Member]
Segment Reporting Information [Line Items]
Capital expenditures	8,634	8,729	11,817
Depreciation and amortization	15,119	11,836	9,594
Accounts receivable	15,296	20,767
Inventory	128,345	117,822
Total segment assets	143,641	138,589
Operating Segments [Member] \| Analytical Solutions Group [Member]
Segment Reporting Information [Line Items]
Capital expenditures	1,763	513	1,228
Depreciation and amortization	1,101	1,252	1,176
Accounts receivable	5,335	5,603
Inventory	3,915	4,391
Total segment assets	9,250	9,994
Operating Segments [Member] \| Europe Region Sales & Service [Member]
Segment Reporting Information [Line Items]
Capital expenditures	183	250	132
Depreciation and amortization	488	348	326
Accounts receivable	6,503	6,538
Inventory	3,241	4,254
Total segment assets	9,744	10,792
Operating Segments [Member] \| Asia Region Sales & Service Operations [Member]
Segment Reporting Information [Line Items]
Capital expenditures	690	857	886
Depreciation and amortization	1,241	1,177	1,711
Accounts receivable	39,046	44,207
Inventory	24,619	25,094
Total segment assets	63,665	69,301
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Capital expenditures	1,913	2,061	3,642
Depreciation and amortization	2,565	2,489	1,635
Accounts receivable	40,182	39,629
Inventory	(4,951)	(8,834)
Total segment assets	$ 35,231	$ 30,795

Business Segment, Geographic Area, Product and Significant Customer Information - Schedule of Capital Expenditures, Depreciation and Amortization Expense and Segment Assets by Reportable Segment (Detail) (USD $)
In Thousands, unless otherwise specified