XML 144 R114.htm IDEA: XBRL DOCUMENT v3.8.0.1
Benefit Plans and Other Postretirement Benefits - Amounts Recognized in the Balance Sheets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Pension Benefits      
Amounts recognized in balance sheet      
Current liabilities $ 0 $ 0  
Non-current liabilities 225 288  
Amounts recognized in accumulated OCI      
Net loss/(gain) (53) (94)  
Prior service cost/(credit) 3 3  
Total accumulated OCI 56 97  
Other changes in plan assets and benefit obligations recognized in other comprehensive income      
Net actuarial (gain)/loss (37) 28  
Amortization of net actuarial (gain)/loss (4) (2) $ (2)
Prior service credit 0 0  
Amortization of prior service cost 0 0  
Total recognized in other comprehensive loss (41) 26  
Net recognized in net periodic pension (credit)/cost and OCI (11) 24  
Estimated unrecognized loss for NRG's pension plan that will be amortized from accumulated OCI to net periodic cost over the next fiscal year (less than) 1    
Significant components of NRG's domestic pension plan      
Projected benefit obligation 1,329 1,241 1,196
Accumulated benefit obligation 1,255 1,174  
Fair value of plan assets 1,104 953 916
Other Postretirement Benefit      
Amounts recognized in balance sheet      
Current liabilities 7 8  
Non-current liabilities 121 120  
Amounts recognized in accumulated OCI      
Net loss/(gain) 4 11  
Prior service cost/(credit) (37) (45)  
Total accumulated OCI (41) (56)  
Other changes in plan assets and benefit obligations recognized in other comprehensive income      
Net actuarial (gain)/loss 6 (2)  
Amortization of net actuarial (gain)/loss 1 0 (1)
Prior service credit (1) (41)  
Amortization of prior service cost 9 5  
Total recognized in other comprehensive loss 15 (38)  
Net recognized in net periodic pension (credit)/cost and OCI 13 39  
Expected unrecognized gain that will be amortized from accumulated OCI to net periodic cost over the next fiscal year 1    
Expected amortization of unrecognized prior service credit over the next fiscal Year   7  
Significant components of NRG's domestic pension plan      
Projected benefit obligation 128 128 178
Fair value of plan assets 0 0 $ 0
GenOn      
Amounts recognized in balance sheet      
Pension benefit obligations 92 120  
Liability retained other post-employment and retiree health and welfare benefits 25    
Amounts recognized in accumulated OCI      
Net loss/(gain) 28    
GenOn | Pension Benefits      
Amounts recognized in balance sheet      
Current liabilities 0 0  
Non-current liabilities 0 0  
Liability retained other post-employment and retiree health and welfare benefits 0 0  
Significant components of NRG's domestic pension plan      
Projected benefit obligation 0 0  
GenOn | Other Postretirement Benefit      
Amounts recognized in balance sheet      
Current liabilities 3 5  
Non-current liabilities 10 16  
Pension benefit obligations 13 21  
Liability retained other post-employment and retiree health and welfare benefits 25 25  
Significant components of NRG's domestic pension plan      
Projected benefit obligation 38 46  
NRG | Pension Benefits      
Amounts recognized in balance sheet      
Current liabilities 0 0  
Non-current liabilities 225 288  
NRG | Other Postretirement Benefit      
Amounts recognized in balance sheet      
Current liabilities 4 3  
Non-current liabilities 111 104  
Discontinued Operations | Pension Benefits      
Amounts recognized in accumulated OCI      
Total accumulated OCI (22) (37)  
Other changes in plan assets and benefit obligations recognized in other comprehensive income      
Total recognized in other comprehensive loss 15 (17)  
Net recognized in net periodic pension (credit)/cost and OCI 15 (17)  
Discontinued Operations | Other Postretirement Benefit      
Amounts recognized in accumulated OCI      
Total accumulated OCI 10 8  
Other changes in plan assets and benefit obligations recognized in other comprehensive income      
Total recognized in other comprehensive loss 2 3  
Net recognized in net periodic pension (credit)/cost and OCI 3 3  
Continuing Operations | Pension Benefits      
Amounts recognized in accumulated OCI      
Total accumulated OCI 34 60  
Other changes in plan assets and benefit obligations recognized in other comprehensive income      
Total recognized in other comprehensive loss (26) 9  
Continuing Operations | Other Postretirement Benefit      
Amounts recognized in accumulated OCI      
Total accumulated OCI (31) (48)  
Other changes in plan assets and benefit obligations recognized in other comprehensive income      
Total recognized in other comprehensive loss $ 17 $ (35)