Pension Benefits - Narrative (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension expense	$ 0	$ 7
Cash contributions to the plans	$ 14	$ 7
Percentage threshold of greater of projected benefit obligation or market value of assets (percent)	10.00%