Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2016

Stockholders' Equity Note [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

The changes in accumulated other comprehensive income (loss) by component for the three and six months endedJune 30, 2016 and 2015, were as follows:

($ in millions)	Benefit Plans			Other			Total
Balance as of March 31, 2015	$	(850	)	$	1		$	(849	)
Other comprehensive income (loss) before reclassifications	—			2			2
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of net actuarial loss (gain)1	22			—			22
Tax benefit (expense) for items of other comprehensive income	(10		)	(1		)	(11		)
Net current period other comprehensive income (loss)	12			1			13
Balance as of June 30, 2015	(838		)	2			(836		)
Balance as of March 31, 2016	(831		)	(2		)	(833		)
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of net actuarial loss (gain)1	19			—			19
Tax benefit (expense) for items of other comprehensive income	(7		)	—			(7		)
Net current period other comprehensive income (loss)	12			—			12
Balance as of June 30, 2016	$	(819	)	$	(2	)	$	(821	)

($ in millions)	Benefit Plans			Other			Total
Balance as of December 31, 2014	$	(864	)	$	2		$	(862	)
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of net actuarial loss (gain)1	44			—			44
Tax benefit (expense) for items of other comprehensive income	(18		)	—			(18		)
Net current period other comprehensive income (loss)	26			—			26
Balance as of June 30, 2015	(838		)	2			(836		)
Balance as of December 31, 2015	(843		)	(2		)	(845		)
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of net actuarial loss (gain)1	39			—			39
Tax benefit (expense) for items of other comprehensive income	(15		)	—			(15		)
Net current period other comprehensive income (loss)	24			—			24
Balance as of June 30, 2016	$	(819	)	$	(2	)	$	(821	)

¹ These accumulated comprehensive income (loss) components are included in the computation of net periodic benefit cost. See Note 16: Employee Pension and Other Postretirement Benefits. The tax benefit associated with amounts reclassified from accumulated other comprehensive income (loss) for the three months endedJune 30, 2016 and 2015, was $7 million and $10 million, respectively. The tax benefit associated with amounts reclassified from accumulated other comprehensive income (loss) for the six months endedJune 30, 2016 and 2015, was $15 million and $18 million, respectively.