Cash flow information (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Interest, net	$ 45,702	$ 39,467
Income taxes paid, net	4,124	4,034
AFUDC borrowed	1,200	1,000
Right-of-use assets obtained in exchange for new operating lease liabilities	24,990	0	$ 0
Property, plant and equipment additions in accounts payable	27,312	30,985	42,355
Debt assumed in connection with a business combination	1,163	0	0
Issuance of common stock in connection with a business combination	0	17,993	$ 18,186
Continuing and discontinued operations
Income taxes paid, net	$ 2,000	$ 3,100