Reclassifications from Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Income (Loss)) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	$ 497
Balance ending	586
Pension and Other Postretirement
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	(24)
Other comprehensive income before reclassifications	0
Amounts reclassified from other comprehensive income	0
Net current-period other comprehensive income	0
Balance ending	(24)
Foreign Currency
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	(14)
Other comprehensive income before reclassifications	0
Amounts reclassified from other comprehensive income	0
Net current-period other comprehensive income	0
Balance ending	(14)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	(38)
Other comprehensive income before reclassifications	0
Amounts reclassified from other comprehensive income	0
Net current-period other comprehensive income	0
Balance ending	$ (38)