Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions			3 Months Ended
		Jan. 01, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), start of period			$ (2,012)		$ (1,567)
Accumulated other comprehensive income (loss), end of period			(2,012)
Reclassification of certain tax effects from accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
Adjustment to adopt new accounting guidance	[1]	$ 0
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), start of period		(1,576)	(2,012)	$ (1,588)	(1,567)	$ (1,684)
Other comprehensive income (loss) before reclassifications			(407)	3
Amounts reclassified from accumulated other comprehensive (income) loss			(38)	(15)
Other comprehensive income (loss)			(445)	(12)
Accumulated other comprehensive income (loss), end of period		(1,576)	(2,012)	(1,588)
Accumulated other comprehensive income (loss) | Reclassification of certain tax effects from accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
Adjustment to adopt new accounting guidance	[1]	108
Foreign currency translation
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), start of period		(1,503)	(1,847)	(1,525)	(1,487)	(1,601)
Other comprehensive income (loss) before reclassifications			(384)	(22)
Amounts reclassified from accumulated other comprehensive (income) loss			24	0
Other comprehensive income (loss)			(360)	(22)
Accumulated other comprehensive income (loss), end of period		(1,503)	(1,847)	(1,525)
Foreign currency translation | Reclassification of certain tax effects from accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
Adjustment to adopt new accounting guidance		98
Pension and other postretirement benefits
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), start of period		31	(10)	24	(3)	12
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive (income) loss			(7)	(7)
Other comprehensive income (loss)			(7)	(7)
Accumulated other comprehensive income (loss), end of period		31	(10)	24
Pension and other postretirement benefits | Reclassification of certain tax effects from accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
Adjustment to adopt new accounting guidance		19
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), start of period		(89)	(157)	(88)	(97)	(80)
Other comprehensive income (loss) before reclassifications			(5)	10
Amounts reclassified from accumulated other comprehensive (income) loss			(55)	(9)
Other comprehensive income (loss)			(60)	1
Accumulated other comprehensive income (loss), end of period		(89)	(157)	(88)
Derivative financial instruments | Reclassification of certain tax effects from accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
Adjustment to adopt new accounting guidance		(9)
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), start of period		(15)	2	1	$ 20	$ (15)
Other comprehensive income (loss) before reclassifications			(18)	15
Amounts reclassified from accumulated other comprehensive (income) loss			0	1
Other comprehensive income (loss)			(18)	16
Accumulated other comprehensive income (loss), end of period		(15)	$ 2	$ 1
Available-for-sale securities | Reclassification of certain tax effects from accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
Adjustment to adopt new accounting guidance		$ 0

[1] See Note 2 for additional information.