Shareholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 1,158	$ 3,583
Other comprehensive income (loss) before reclassifications, net	4	(58)
Amounts reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income	32	37
Tax expense	(8)	(9)
Amounts reclassified from accumulated other comprehensive income, net	24	28
Net current period other comprehensive income (loss)	28	(30)
Ending Balance	1,291	4,361
Change in Fair Value of Financial Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	2	1
Other comprehensive income (loss) before reclassifications, net	0	10
Amounts reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income	1	1
Tax expense	0	0
Amounts reclassified from accumulated other comprehensive income, net	1	1
Net current period other comprehensive income (loss)	1	11
Ending Balance	3	12
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(1,333)	(1,045)
Other comprehensive income (loss) before reclassifications, net	(6)	(70)
Amounts reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income	0	0
Tax expense	0	0
Amounts reclassified from accumulated other comprehensive income, net	0	0
Net current period other comprehensive income (loss)	(6)	(70)
Ending Balance	(1,339)	(1,115)
Postretirement Benefit Obligation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(2,540)	(2,817)
Other comprehensive income (loss) before reclassifications, net	10	2
Amounts reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income	31	36
Tax expense	(8)	(9)
Amounts reclassified from accumulated other comprehensive income, net	23	27
Net current period other comprehensive income (loss)	33	29
Ending Balance	(2,507)	(2,788)
AOCI Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(3,871)	(3,861)
Amounts reclassified from accumulated other comprehensive income
Ending Balance	$ (3,843)	$ (3,891)