Acquisitions - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013 Aarding Thermal Acoustics B.V. ("Aarding") [Member] USD ($)	Dec. 31, 2013 Aarding Thermal Acoustics B.V. ("Aarding") [Member] EUR (€)	Dec. 31, 2013 Adwest Technologies, Inc. ('Adwest') [Member] USD ($)	Dec. 31, 2012 Adwest Technologies, Inc. ('Adwest') [Member] USD ($)	Dec. 31, 2013 Met-Pro and Aarding [Member] USD ($)	Dec. 31, 2013 Met-Pro [Member] USD ($)	Dec. 31, 2013 Met-Pro [Member] Maximum [Member]	Dec. 31, 2013 Met-Pro [Member] Minimum [Member]
Business Acquisition [Line Items]
Cash paid on acquisition	$ 24,400,000				$ 125,400,000
Company's common stock	763,673	763,673		53,000
Fair value of common stock issued	6,800,000
Business combination contingent consideration paid	5,500,000	4,000,000
Prepaid compensation recognized in Prepaid expenses and other current assets	1,100,000
Prepaid compensation recognized in Deferred Charges and other assets	3,500,000
Business combination compensation expenses	900,000
Earn out payment upon attainment of specified financial targets through December 31, 2017	7,600,000	5,500,000
Earn out expenses	1,300,000		1,700,000
Earn out expenses included in accounts payable and accrued expenses	1,300,000
Cash consideration per share						$ 13.75
Stock consideration per share						$ 13.75
Exchange ratio						1.0843	1.3520	1.0000
Percentage of common stock converted into cash						51.60%
Value of shares transferred for cash						104,400,000
Trading day period						15 days
Trading price						$ 12.6814
Shares of common stock in aggregate stock consideration						7,726,235
Percentage of cash consideration						77.56%
Percentage of stock consideration						22.44%
Value of stock recorded						98,000,000
Consideration for cancelling of options and restricted stock units						4,900,000
Revenue contributed					68,100,000
Net income contributed					200,000
Consideration paid in common stock issued					104,800,000
Goodwill expected to be deductible for tax purposes					112,400,000
Cash paid on acquisition				4,000,000
Worth of Company's common stock				$ 500,000