XML 87 R62.htm IDEA: XBRL DOCUMENT v3.10.0.1
Fair Value Measurements - Level 3 Rollforward Derivatives (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]        
Net derivative balance at beginning of period $ (19,754) $ (41,685) $ (18,256) $ (47,406)
Included in OCI 0 (6) 0 (6)
Deferred as a regulatory asset or liability (989) 4,252 (3,311) (7,503)
Settlements 494 1,699 1,276 3,122
Transfers into Level 3 from Level 2 (2,534) (4,350) (4,979) (4,388)
Transfers from Level 3 into Level 2 13,425 3,845 15,912 19,936
Net derivative balance at end of period (9,358) (36,245) (9,358) (36,245)
Net unrealized gains included in earnings related to instruments still held at end of period $ 0 $ 0 $ 0 $ 0