v3.10.0.1
Financial information by segment, Assets and liabilities by geography (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Jun. 30, 2017
Dec. 31, 2016
Assets [Abstract]        
Contracted concessional assets $ 8,736,368 $ 9,084,270    
Investments carried under the equity method 53,002 55,784    
Current financial investments 215,148 210,138    
Cash and cash equivalents (project companies) 657,212 669,387 $ 614,312 $ 594,811
Total assets 10,157,276 10,492,339    
Liabilities [Abstract]        
Long-term and short-term project debt 5,218,820 5,475,208    
Grants and other liabilities 1,662,379 1,636,060    
Long-term and short-term corporate debt 639,041 643,083    
Total liabilities 8,293,042 8,596,886    
Equity 1,864,234 1,895,453 $ 2,013,130 $ 1,959,111
Total liabilities and equity 10,157,276 10,492,339    
North America [Member]        
Assets [Abstract]        
Contracted concessional assets 3,600,231 3,770,169    
Investments carried under the equity method 0 0    
Current financial investments 118,344 116,451    
Cash and cash equivalents (project companies) 161,906 149,236    
Total assets 3,880,481 4,035,856    
Liabilities [Abstract]        
Long-term and short-term project debt 1,755,091 1,821,102    
Grants and other liabilities 1,564,805 1,593,048    
Total liabilities 3,319,896 3,414,150    
South America [Member]        
Assets [Abstract]        
Contracted concessional assets 1,091,274 1,100,778    
Investments carried under the equity method 0 0    
Current financial investments 62,020 59,831    
Cash and cash equivalents (project companies) 41,920 42,548    
Total assets 1,195,214 1,203,157    
Liabilities [Abstract]        
Long-term and short-term project debt 860,051 876,063    
Grants and other liabilities 5,194 810    
Total liabilities 865,245 876,873    
EMEA [Member]        
Assets [Abstract]        
Contracted concessional assets 4,044,863 4,213,323    
Investments carried under the equity method 53,002 55,784    
Current financial investments 34,014 31,263    
Cash and cash equivalents (project companies) 301,115 329,078    
Total assets 4,432,994 4,629,448    
Liabilities [Abstract]        
Long-term and short-term project debt 2,603,678 2,778,043    
Grants and other liabilities 92,380 42,202    
Total liabilities 2,696,058 2,820,245    
Allocated [Member]        
Assets [Abstract]        
Contracted concessional assets 8,736,368 9,084,270    
Investments carried under the equity method 53,002 55,784    
Current financial investments 214,378 207,545    
Cash and cash equivalents (project companies) 504,941 520,862    
Total assets 9,508,689 9,868,461    
Liabilities [Abstract]        
Long-term and short-term project debt 5,218,820 5,475,208    
Grants and other liabilities 1,662,379 1,636,060    
Total liabilities 6,881,199 7,111,268    
Unallocated [Member]        
Assets [Abstract]        
Other non-current assets 216,771 210,378    
Other current assets (including cash and cash equivalents at holding company level) 431,816 413,500    
Total assets 648,587 623,878    
Liabilities [Abstract]        
Long-term and short-term corporate debt 639,041 643,083    
Other non-current liabilities 591,456 657,345    
Other current liabilities 181,346 185,190    
Total liabilities 1,411,843 1,485,618    
Equity 1,864,234 1,895,453    
Total liabilities and equity $ 3,276,077 $ 3,381,071