v3.8.0.1
Schedule I, Condensed Financial Statements, of condensed other comprehensive income statement (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Other comprehensive income statement [Abstract]      
Profit/(loss) for the year $ (104,887) $ 1,667 $ (198,186)
Items that may be subject to transfer to income statement [Abstract]      
Change in fair value of cash flow hedges (28,535) (37,480) 56
Net income/(expenses) recognized directly in equity 97,815 (47,075) (89,399)
Cash flow hedges 70,953 72,774 55,841
Transfer to income statement 53,215 54,580 41,881
Other comprehensive income/(loss) 151,030 7,505 (47,518)
Total comprehensive income/(loss) for the year 46,143 9,172 (245,704)
Parent Company [Member]      
Other comprehensive income statement [Abstract]      
Profit/(loss) for the year 52,565 31,263 (219,615)
Items that may be subject to transfer to income statement [Abstract]      
Change in fair value of cash flow hedges (13,666) 7,213 3,683
Net income/(expenses) recognized directly in equity (13,666) 7,213 3,683
Cash flow hedges (32) 2,321 662
Transfer to income statement (32) 2,321 662
Other comprehensive income/(loss) (13,698) 9,534 4,345
Total comprehensive income/(loss) for the year $ 38,867 $ 40,797 $ (215,270)