Derivative Instruments - Schedule of Gross and Net Amount Offset (Details) - Balance Sheet Offsetting $ in Millions	Dec. 31, 2016 USD ($)
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	$ 43
Counterparty Offsetting	16
Net Fair Value in the Consolidated Balance Sheets	27
Counterparty A
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	12
Counterparty Offsetting	6
Net Fair Value in the Consolidated Balance Sheets	6
Counterparty B
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	4
Counterparty Offsetting	2
Net Fair Value in the Consolidated Balance Sheets	2
Counterparty C
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	4
Counterparty Offsetting	1
Net Fair Value in the Consolidated Balance Sheets	3
Counterparty D
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	9
Counterparty Offsetting	3
Net Fair Value in the Consolidated Balance Sheets	6
Counterparty E
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	4
Counterparty Offsetting	2
Net Fair Value in the Consolidated Balance Sheets	2
Counterparty F
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	4
Counterparty Offsetting	2
Net Fair Value in the Consolidated Balance Sheets	2
Counterparty G
Change in unrealized gain (loss) on anticipated sales hedging:
Gross Fair Value	6
Counterparty Offsetting	0
Net Fair Value in the Consolidated Balance Sheets	$ 6