Segment Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Revenues Gross Profit And Operating Income By Segment [Table Text Block]

Revenues, gross profit, and operating income associated with our segments were as follows:

	Year Ended December 31,
	2017			2016			2015
	(in thousands)
Revenues
Electricity	$	1,022,939		$	938,374		$	820,306
Gas	533,624			569,476			543,805
Water	461,634			505,336			519,422
Total Company	$	2,018,197		$	2,013,186		$	1,883,533
Gross profit
Electricity	$	318,953		$	282,677		$	225,446
Gas	191,303			205,063			185,559
Water	164,898			172,580			145,680
Total Company	$	675,154		$	660,320		$	556,685
Operating income
Electricity	$	93,566		$	68,287		$	31,104
Gas	74,206			66,813			67,471
Water	44,494			37,266			19,864
Corporate unallocated	(60,840		)	(76,155		)	(65,593		)
Total Company	151,426			96,211			52,846
Total other income (expense)	(16,851		)	(11,584		)	(15,744		)
Income before income taxes	$	134,575		$	84,627		$	37,102

Revenues By Region [Table Text Block]

Revenues by region were as follows:

	Year Ended December 31,
	2017		2016		2015
	(in thousands)
United States and Canada	$	1,137,508	$	1,126,787	$	997,293
Europe, Middle East, and Africa (EMEA)	672,942		698,106		701,301
Other	207,747		188,293		184,939
Total Company	$	2,018,197	$	2,013,186	$	1,883,533

Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]

Property, plant, and equipment, net, by geographic area were as follows:

	At December 31,
	2017		2016
	(in thousands)
United States	$	67,764	$	70,435
Outside United States	133,004		106,023
Total Company	$	200,768	$	176,458

Depreciation And Amortization Expense Associated With Segments [Table Text Block]

Depreciation and amortization expense associated with our segments was as follows:

	Year Ended December 31,
	2017		2016		2015
	(in thousands)
Electricity	$	24,703	$	28,468	$	35,896
Gas	18,800		20,714		20,288
Water	16,092		18,675		19,459
Corporate unallocated	3,620		461		350
Total Company	$	63,215	$	68,318	$	75,993