Aclara Divestiture (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	Jun. 15, 2015	Mar. 28, 2014	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Net sales			$ 159,505	$ 140,191	$ 138,930	$ 132,833	$ 153,612	$ 134,191	$ 128,941	$ 120,547	$ 571,459	$ 537,291	$ 531,120
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax, Total											$ 0	776	(52,061)
Aclara Technologies LLC [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax												$ 1,200	(48,200)
Net sales													129,600
Proceeds from Divestiture of Businesses, Net of Cash Divested, Total		$ 135,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax, Total													63,800
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax													$ 15,600
Repayments of Other Debt	$ 2,300