Segments, Concentrations and Geographic Information (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		$ 223,357	$ 182,674	$ 438,792	$ 363,127
Income from operations		23,149	16,175	40,811	31,152
Restructuring		(1,198)	(1,641)	(3,096)	(3,194)
Net interest expense		2,031	2,904	3,736	5,800
Other non-operating income, net		(136)	(205)	(666)	(483)
Loss on extinguishment of convertible debt				1,797
Total other non-operating (income) expense, net		1,895	2,699	4,867	5,317
Income before income taxes		21,254	13,476	35,944	25,835
Provision for income taxes		5,870	4,127	10,234	7,676
Net income		15,384	9,349	25,710	18,159
Total depreciation and amortization		8,809	7,488	17,615	14,749
Total assets		911,087	869,824	911,087	869,824	$ 869,824
North America (primarily U.S.) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		115,236	104,779	230,376	216,962
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		84,983	59,237	168,275	111,351
Asia And Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		23,138	18,658	40,141	34,814
Operating Segments [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Restructuring		(1,198)	(1,641)	(3,096)	(3,194)
Operating Segments [Member] | Couplings, Clutches and Brakes [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		110,969	78,157	217,201	153,780
Income from operations		12,007	7,554	20,352	13,845
Restructuring		(488)	(1,089)	(1,849)	(1,493)
Total depreciation and amortization		5,133	3,770	10,270	7,458
Total assets		557,642	511,934	557,642	511,934
Operating Segments [Member] | Electromagnetic Clutches and Brakes [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		65,281	57,053	129,159	114,402
Income from operations		8,163	7,068	15,756	13,531
Restructuring			(345)		(1,017)
Total depreciation and amortization		1,201	1,177	2,416	2,325
Total assets		185,839	169,507	185,839	169,507
Operating Segments [Member] | Gearing [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		49,149	49,096	96,177	98,015
Income from operations		6,590	5,867	12,115	11,629
Restructuring		(488)		(784)	(16)
Total depreciation and amortization		1,651	1,728	3,301	3,398
Total assets		137,713	147,829	137,713	147,829
Intersegment Eliminations [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales		(2,042)	(1,632)	(3,745)	(3,070)
Corporate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Income from operations	[1]	(2,413)	(2,673)	(4,316)	(4,659)
Restructuring		(222)	(207)	(463)	(668)
Total depreciation and amortization		824	813	1,628	1,568
Total assets	[2]	$ 29,893	$ 40,554	$ 29,893	$ 40,554

[1] Certain expenses are maintained at the corporate level and not allocated to the segments. These include various administrative expenses related to corporate headquarters, depreciation on capitalized software costs, non-capitalizable software implementation costs and acquisition related expenses and non-cash partial pension settlements.

[2] Corporate assets are primarily cash and cash equivalents, tax related asset accounts, certain capitalized software costs, property, plant and equipment and deferred financing costs.