XML 83 R59.htm IDEA: XBRL DOCUMENT v3.3.1.900
Comprehensive income (loss) (Details 14) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Accumulated other comprehensive income (loss) [Roll Forward]      
Balance $ 3,249,784 $ 2,855,902 $ 2,648,248
Amounts reclassified from accumulated other comprehensive loss (3,131) (1,625)  
Net current-period other comprehensive income (loss) 4,955 (3,898) 10,516
Balance 2,520,548 3,249,784 2,855,902
Net unrealized gain (loss) on derivative instruments qualifying as hedges      
Accumulated other comprehensive income (loss) [Roll Forward]      
Balance (3,071) (3,765)  
Other comprehensive income (loss) before reclassifications 0 0  
Amounts reclassified from accumulated other comprehensive loss 404 694  
Amounts reclassified from accumulated other comprehensive loss to a regulatory asset 0 0  
Net current-period other comprehensive income (loss) 404 694  
Balance (2,667) (3,071) (3,765)
Postretirement liability adjustment      
Accumulated other comprehensive income (loss) [Roll Forward]      
Balance (38,218) (33,807)  
Other comprehensive income (loss) before reclassifications (88) (12,409)  
Amounts reclassified from accumulated other comprehensive loss 1,794 796  
Amounts reclassified from accumulated other comprehensive loss to a regulatory asset 2,255 7,202  
Net current-period other comprehensive income (loss) 3,961 (4,411)  
Balance (34,257) (38,218) (33,807)
Foreign currency translation adjustment      
Accumulated other comprehensive income (loss) [Roll Forward]      
Balance (829) (667)  
Other comprehensive income (loss) before reclassifications (173) (162)  
Amounts reclassified from accumulated other comprehensive loss 802 0  
Amounts reclassified from accumulated other comprehensive loss to a regulatory asset 0 0  
Net current-period other comprehensive income (loss) 629 (162)  
Balance (200) (829) (667)
Net unrealizaed gasin (loss) on available-for-sale investments      
Accumulated other comprehensive income (loss) [Roll Forward]      
Balance 15 34  
Other comprehensive income (loss) before reclassifications (170) (154)  
Amounts reclassified from accumulated other comprehensive loss 131 135  
Amounts reclassified from accumulated other comprehensive loss to a regulatory asset 0 0  
Net current-period other comprehensive income (loss) (39) (19)  
Balance (24) 15 34
Accumulated other comprehensive loss      
Accumulated other comprehensive income (loss) [Roll Forward]      
Balance (42,103) (38,205) (48,721)
Other comprehensive income (loss) before reclassifications (431) (12,725)  
Amounts reclassified from accumulated other comprehensive loss 3,131 1,625  
Amounts reclassified from accumulated other comprehensive loss to a regulatory asset 2,255 7,202  
Net current-period other comprehensive income (loss) 4,955 (3,898) 10,516
Balance $ (37,148) $ (42,103) $ (38,205)