XML 65 R51.htm IDEA: XBRL DOCUMENT v3.10.0.1
Fair Value of Financial Assets and Liabilities, Financial Impact of Qualifying Cash Flow Hedges (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Financial Impact of Qualifying Cash Flow Hedges on Accumulated Other Comprehensive Income (Loss) [Roll Forward]      
Accumulated other comprehensive loss related to cash flow hedges at Jan. 1 $ (800) $ (700) $ (800)
After-tax net realized losses on derivative transactions reclassified into earnings (100) 0 (100)
Adoption of ASU. 2018-02 (a) [1] 0 (100) 0
Accumulated other comprehensive loss related to cash flow hedges at Dec. 31 $ (700) $ (800) $ (700)
[1] In 2017, SPS implemented ASU No. 2018-02 related to TCJA, which resulted in reclassification of certain credit balances within net accumulated other comprehensive loss to retained earnings.