AOCL (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (1,666)	$ (1,623)	$ (1,666)	$ (1,623)		$ (1,770)
Other Comprehensive Income (Loss), Net of Tax	(20)	(19)	(104)	(42)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(55)	(53)	(55)	(53)	$ (55)	(55)	$ (53)	$ (56)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0	3
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(1,611)	(1,570)	(1,611)	(1,570)	$ (1,631)	$ (1,715)	$ (1,589)	$ (1,609)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	67	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0	87	0
Other Comprehensive Income (Loss) before Reclassifications, Tax	0	0	(20)	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	27	25	49	51
Reclassification from AOCI, Current Period, Tax	(7)	(6)	(12)	(12)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	20	19	37	39
Other Comprehensive Income (Loss), Net of Tax	$ 20	$ 19	$ 104	$ 39