v3.8.0.1
Financial information by segment, Assets and liabilities by geography (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Assets [Abstract]        
Contracted concessional assets $ 9,084,270 $ 8,924,272    
Investments carried under the equity method 55,784 55,009 $ 56,181  
Current financial investments 210,138 228,038    
Cash and cash equivalents (project companies) 669,387 594,811 514,712 $ 354,154
Total assets 10,492,339 10,297,799    
Liabilities [Abstract]        
Long-term and short-term project debt 5,475,208 5,330,467 5,470,669  
Grants and other liabilities 1,636,060 1,612,045    
Long-term and short-term corporate debt 643,083 668,201    
Total liabilities 8,596,886 8,338,688    
Equity 1,895,453 1,959,111 $ 2,023,501 $ 1,839,631
Total liabilities and equity 10,492,339 10,297,799    
North America [Member]        
Assets [Abstract]        
Contracted concessional assets 3,770,169 3,920,106    
Investments carried under the equity method 0 0    
Current financial investments 116,451 136,665    
Cash and cash equivalents (project companies) 149,236 185,970    
Total assets 4,035,856 4,242,741    
Liabilities [Abstract]        
Long-term and short-term project debt 1,821,102 1,870,861    
Grants and other liabilities 1,593,048 1,575,303    
Total liabilities 3,414,150 3,446,164    
South America [Member]        
Assets [Abstract]        
Contracted concessional assets 1,100,778 1,144,712    
Investments carried under the equity method 0 0    
Current financial investments 59,831 62,215    
Cash and cash equivalents (project companies) 42,548 40,015    
Total assets 1,203,157 1,246,942    
Liabilities [Abstract]        
Long-term and short-term project debt 876,063 895,316    
Grants and other liabilities 810 1,512    
Total liabilities 876,873 896,828    
EMEA [Member]        
Assets [Abstract]        
Contracted concessional assets 4,213,323 3,859,454    
Investments carried under the equity method 55,784 55,009    
Current financial investments 31,263 29,158    
Cash and cash equivalents (project companies) 329,078 246,671    
Total assets 4,629,448 4,190,291    
Liabilities [Abstract]        
Long-term and short-term project debt 2,778,043 2,564,290    
Grants and other liabilities 42,202 35,230    
Total liabilities 2,820,245 2,599,520    
Allocated [Member]        
Assets [Abstract]        
Contracted concessional assets 9,084,270 8,924,272    
Investments carried under the equity method 55,784 55,009    
Current financial investments 207,545 228,038    
Cash and cash equivalents (project companies) 520,862 472,656    
Total assets 9,868,461 9,679,975    
Liabilities [Abstract]        
Long-term and short-term project debt 5,475,208 5,330,467    
Grants and other liabilities 1,636,060 1,612,045    
Total liabilities 7,111,268 6,942,512    
Unallocated [Member]        
Assets [Abstract]        
Other non-current assets 210,378 272,664    
Other current assets (including cash and cash equivalents at holding company level) 413,500 345,160    
Total assets 623,878 617,824    
Liabilities [Abstract]        
Long-term and short-term corporate debt 643,083 668,201    
Other non-current liabilities 657,345 546,053    
Other current liabilities 185,190 181,922    
Total liabilities 1,485,618 1,396,176    
Equity 1,895,453 1,959,111    
Total liabilities and equity $ 3,381,071 $ 3,355,287