Acquisitions - (PMFG) - Additional Information (Detail) - PMFG, Inc. [Member] - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 03, 2015	Dec. 31, 2016	Dec. 31, 2015	Jul. 11, 2016
Business Acquisition [Line Items]
Equity interests acquired	100.00%
Purchase price of acquisition	$ 136,700
Cash consideration per share	$ 6.85	$ 9.49
Stock consideration per share	$ 6.85
Trading day period	15 days
Percentage of common stock converted into cash	44.50%
Value of shares transferred for cash	$ 64,600
Trading price	$ 9.6655
Exchange ratio	0.6456
Shares of common stock in aggregate stock consideration	7,602,166
Percentage of cash consideration		58.05%
Percentage of stock consideration		41.95%
Value of stock recorded for purchase accounting		$ 72,100
Fair value of noncontrolling interest		4,212
Revenue from acquired entity		101,700	$ 40,800
Income from acquired entity		$ 13,100	$ 2,200
Peerless Propulsys [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		60.00%
Percentage of ownership by parent in net income loss		80.00%
Promissory note issued in exchange for ownership in equity		$ 5,300
Promissory note due date		Jul. 11, 2019
Ownership interest in the equity and earnings		100.00%
Business combination acquisition of minority interest caring value				$ 4,100
Fair value of noncontrolling interest				$ 5,300
Additional paid in capital noncontrolling interest excess payment for existing equity investment		$ 1,200
Notes payable amount outstanding		$ 5,300
Debt Instrument, Term		30 days
Notes payable description		The note is payable at the earlier of July 11, 2019 or thirty days subsequent to the sale of building and land that the Company owns in China.
Building and land expected for sale, period		1 year
Asset held for sale, carrying value		$ 5,400
Maximum [Member]
Business Acquisition [Line Items]
Common stock shares exchange ratio per share	0.6456
Minimum [Member]
Business Acquisition [Line Items]
Common stock shares exchange ratio per share	0.5282