Business Segment Information - Property and Equipment Additions, Depreciation and Amortization and Identifiable Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Property and equipment additions	$ 1,377	$ 273
Depreciation and amortization	6,647	1,250
Identifiable Assets	348,536	94,104
Engineered Equipment Technology and Parts [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	522	113
Depreciation and amortization	2,753	623
Identifiable Assets	116,647	60,516
Met-Pro [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	680
Depreciation and amortization	3,365
Identifiable Assets	217,695
Contracting / Services [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	30	61
Depreciation and amortization	210	221
Identifiable Assets	7,026	8,055
Component Parts [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	141	77
Depreciation and amortization	188	193
Identifiable Assets	5,946	5,573
Corporate [Member]
Segment Reporting Information [Line Items]
Property and equipment additions	4	22
Depreciation and amortization	131	213
Identifiable Assets	$ 1,222	$ 19,960