Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive Income (Loss)

21. Accumulated Other Comprehensive Income (Loss)

The following summarizes the after-tax changes in the balances of accumulated other comprehensive income (loss):

millions	Interest-rate Derivatives Previously Subject to Hedge Accounting			Pension and Other Postretirement Plans			Total
Balance at December 31, 2014	$	(48	)	$	(469	)	$	(517	)
Other comprehensive income (loss), before reclassifications	—			87			87
Reclassifications to Consolidated Statement of Income	6			41			47
Net other comprehensive income (loss)	6			128			134
Balance at December 31, 2015	$	(42	)	$	(341	)	$	(383	)
Other comprehensive income (loss), before reclassifications	—			(107		)	(107		)
Reclassifications to Consolidated Statement of Income	5			94			99
Net other comprehensive income (loss)	5			(13		)	(8		)
Balance at December 31, 2016	$	(37	)	$	(354	)	$	(391	)
Other comprehensive income (loss), before reclassifications	—			(10		)	(10		)
Reclassifications to Consolidated Statement of Income	2			61			63
Net other comprehensive income (loss)	2			51			53
Balance at December 31, 2017	$	(35	)	$	(303	)	$	(338	)