Pension and Postretirement Benefit Plans - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 plan
Defined Benefit Plan Disclosure [Line Items]
Pension settlement charge	$ 258		$ 258
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Number Of Plans Terminated | plan					1
Pension settlement charge	258		258
Pension Plan [Member] | UNITED STATES | Terminated Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to the terminated plan	62
Unfunded pension obligation reduction	165		$ 165
Pension settlement charge	$ 258