Senior Debt - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Jul. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Oct. 01, 2017	Jan. 01, 2017	Dec. 31, 2016	Jul. 12, 2016
Line Of Credit Facility [Line Items]
Prepayment of outstanding debt		$ 2,300,000
Scheduled payments of debt		1,700,000
Repayments of debt		4,038,000	$ 3,215,000
Long-term debt, principal payment remainder of 2017		6,700,000
Long-term debt, principal payment 2018		9,200,000
Long-term debt, principal payment 2019		10,800,000
Long-term debt, principal payment 2020		$ 95,700,000
Weighted average stated interest rate on outstanding borrowings		3.41%				3.26%
Interest rate swap, fair value						$ 200,000
Changes in fair value income (loss)			$ 500,000
Maximum consolidated leverage ratio		325.00%			325.00%
Minimum fixed charge coverage ratio		125.00%
Increased interest rate of loan due to default		2.00%
ING Bank N.V. ("Aarding") [Member]
Line Of Credit Facility [Line Items]
Total borrowing capacity		$ 13,900,000				13,900,000
ING Bank N.V. ("Aarding") [Member] | Bank Overdrafts [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities		$ 0				0
Peerless Propulsys [Member]
Line Of Credit Facility [Line Items]
Ownership interest in the equity and earnings							100.00%
Peerless Propulsys [Member] | PMFG, Inc. [Member]
Line Of Credit Facility [Line Items]
Interest rate	1.50%
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	$ 5,300,000
Promissory note due date	Jul. 11, 2019
Ownership interest in the equity and earnings	100.00%
Notes payable amount outstanding		$ 5,300,000				5,300,000
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
Scenario Forecast [Member]
Line Of Credit Facility [Line Items]
Maximum consolidated leverage ratio				300.00%
Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Unused credit availability under credit facility		$ 58,700,000				62,000,000
Letters of Credit [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities		21,300,000				18,000,000
Bank Guarantee Facility [Member] | ING Bank N.V. ("Aarding") [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities		4,400,000				5,300,000
China Facility [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities		$ 1,306,000				$ 1,296,000
Interest rate		4.79%
Debt instrument maturity period		2017-05