Accounting for Derivative Instruments and Hedging Activities (Tables)

6 Months Ended

Jun. 30, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Net notional volume buy/(sell) of NRG's open derivative transactions broken out by commodity

The following table summarizes the net notional volume buy/(sell) of NRG's open derivative transactions broken out by category, excluding those derivatives that qualified for the NPNS exception, as of June 30, 2019 and December 31, 2018. Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date.

		Total Volume
		June 30, 2019			December 31, 2018
Category	Units	(In millions)
Emissions	Short Ton	1			(2		)
Renewable Energy Certificates	Certificates	1			1
Coal	Short Ton	7			13
Natural Gas	MMBtu	(238		)	(330		)
Oil	Barrels	—			1
Power	MWh	21			1
Capacity	MW/Day	(1		)	(1		)
Interest	Dollars	$	—		$	1,000

Fair value within the derivative instrument valuation on the balance sheets

The following table summarizes the fair value within the derivative instrument valuation on the balance sheets:

	Fair Value
	Derivative Assets				Derivative Liabilities
	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
	(In millions)
Derivatives Not Designated as Cash Flow or Fair Value Hedges:
Interest rate contracts current	$	—	$	17	$	—	$	—
Interest rate contracts long-term	—		22		—		—
Commodity contracts current	850		747		778		673
Commodity contracts long-term	426		295		374		304
Total Derivatives Not Designated as Cash Flow or Fair Value Hedges	$	1,276	$	1,081	$	1,152	$	977

Offsetting of derivatives by counterparty assets

The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid:

	Gross Amounts Not Offset in the June 30, 2019 Balance Sheet
	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
	(In millions)
Commodity contracts:
Derivative assets	$	1,276		$	(1,029	)	$	(10	)	$	237
Derivative liabilities	(1,152		)	1,029			58			(65		)
Total commodity contracts	$	124		$	—		$	48		$	172

	Gross Amounts Not Offset in the December 31, 2018 Balance Sheet
	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
	(In millions)
Commodity contracts:
Derivative assets	$	1,042		$	(778	)	$	(31	)	$	233
Derivative liabilities	(977		)	778			114			(85		)
Total commodity contracts	65			—			83			148
Interest rate contracts:
Derivative assets	39			—			—			39
Total interest rate contracts	39			—			—			39
Total derivative instruments	$	104		$	—		$	83		$	187

Offsetting of derivatives by counterparty, liabilities

The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid:

	Gross Amounts Not Offset in the June 30, 2019 Balance Sheet
	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
	(In millions)
Commodity contracts:
Derivative assets	$	1,276		$	(1,029	)	$	(10	)	$	237
Derivative liabilities	(1,152		)	1,029			58			(65		)
Total commodity contracts	$	124		$	—		$	48		$	172

	Gross Amounts Not Offset in the December 31, 2018 Balance Sheet
	Gross Amounts of Recognized Assets / Liabilities			Derivative Instruments			Cash Collateral (Held) / Posted			Net Amount
	(In millions)
Commodity contracts:
Derivative assets	$	1,042		$	(778	)	$	(31	)	$	233
Derivative liabilities	(977		)	778			114			(85		)
Total commodity contracts	65			—			83			148
Interest rate contracts:
Derivative assets	39			—			—			39
Total interest rate contracts	39			—			—			39
Total derivative instruments	$	104		$	—		$	83		$	187

Effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax

The following table summarizes the effects on the Company's accumulated OCL balance attributable to cash flow hedge derivatives, net of tax:

	Interest Rate Contracts
	Three months ended June 30, 2018			Six months ended June 30, 2018
	(In millions)
Accumulated OCL beginning balance	$	(31	)	$	(54	)
Reclassified from accumulated OCL to income:
Due to realization of previously deferred amounts	3			7
Mark-to-market of cash flow hedge accounting contracts	5			24
Accumulated OCL ending balance, net of $5 tax	$	(23	)	$	(23	)

Pre-tax effects of economic hedges that have not been designated as cash flow hedges, ineffectiveness on cash flow hedges and trading activity on the Company's statement of operations

The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the Company's statement of operations. The effect of commodity hedges is included within operating revenues and cost of operations and the effect of interest rate hedges is included in interest expense.

	Three months ended June 30,						Six months ended June 30,
	2019			2018			2019			2018
Unrealized mark-to-market results	(In millions)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to economic hedges	$	11		$	(2	)	$	30		$	(1	)
Reversal of acquired loss/(gain) positions related to economic hedges	1			(1		)	(1		)	(1		)
Net unrealized gains/(losses) on open positions related to economic hedges	9			(73		)	12			132
Total unrealized mark-to-market gains/(losses) for economic hedging activities	21			(76		)	41			130
Reversal of previously recognized unrealized gains on settled positions related to trading activity	(1		)	(3		)	(7		)	(6		)
Net unrealized gains on open positions related to trading activity	13			8			26			19
Total unrealized mark-to-market gains for trading activity	12			5			19			13
Total unrealized gains/(losses)	$	33		$	(71	)	$	60		$	143

	Three months ended June 30,						Six months ended June 30,
	2019			2018			2019			2018
	(In millions)
Unrealized gains/(losses) included in operating revenues	$	253		$	15		$	280		$	(73	)
Unrealized (losses)/gains included in cost of operations	(220		)	(86		)	(220		)	216
Total impact to statement of operations — energy commodities	$	33		$	(71	)	$	60		$	143
Total impact to statement of operations — interest rate contracts	$	(29	)	$	3		$	(38	)	$	15