Employee Benefits (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Schedule of Components of Net Periodic Pension Benefit (Income) Expense and Post-retirement Benefit Expense

Net periodic benefit income for the Lumen Combined Pension Plan ("Combined Pension Plan") includes the following components:

	Combined Pension Plan
	Three Months Ended March 31,
	2021		2020
	(Dollars in millions)
Service cost	$	13	16
Interest cost	50		82
Expected return on plan assets	(138)		(149)
Recognition of prior service credit	(2)		(3)
Recognition of actuarial loss	49		50
Net periodic pension benefit income	$	(28)	(4)

Net periodic benefit expense for our post-retirement benefit plans includes the following components:

	Post-Retirement Benefit Plans
	Three Months Ended March 31,
	2021		2020
	(Dollars in millions)
Service cost	$	4	4
Interest cost	12		20
Recognition of prior service cost	4		4
Recognition of actuarial loss	1		—
Net periodic post-retirement benefit expense	$	21	28