Cash flow information (Details 1) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Interest, net of amount capitalized and AFUDC - borrowed of $196 and $260 in 2017 and 2016, respectively		$ 17,546	$ 23,109
Income taxes refunded, net	[1]	(2,762)	(1,429)
Property, plant and equipment additions in accounts payable		5,212	23,277
Capitalized interest and AFUDC borrowed		196	260
Continuing and discontinued operations [Member]
Income taxes refunded, net		$ (7,200)	$ (1,400)

[1] Income taxes refunded, net of discontinued operations, were $(7.2) million and $(1.4) million for the three months ended March 31, 2017 and 2016, respectively.