Employee and Agent Benefits (Tables)

12 Months Ended

Dec. 31, 2020

Defined Benefit Plans and Other Postretirement Benefit Plans

Obligations and Funded Status (Table)

					Other postretirement
	Pension benefits				benefits
	December 31,				December 31,
	2020		2019		2020		2019
	(in millions)
Change in benefit obligation
Benefit obligation at beginning of year	$	(3,692.1)	$	(3,239.2)	$	(101.4)	$	(98.9)
Service cost		(72.7)		(66.0)		—		—
Interest cost		(117.3)		(126.5)		(2.8)		(3.7)
Actuarial loss		(462.4)		(506.4)		(11.7)		(4.8)
Participant contributions		—		—		(6.0)		(4.4)
Benefits paid		134.3		123.6		12.8		12.2
Plan amendments		—		122.4		1.0		(1.8)
Other		—		—		0.1		—
Benefit obligation at end of year	$	(4,210.2)	$	(3,692.1)	$	(108.0)	$	(101.4)
Change in plan assets
Fair value of plan assets at beginning of year	$	2,926.0	$	2,498.2	$	732.8	$	643.9
Actual return on plan assets		521.3		520.9		53.1		95.5
Employer contribution		60.5		30.5		1.5		1.2
Participant contributions		—		—		6.0		4.4
Benefits paid		(134.3)		(123.6)		(12.8)		(12.2)
Fair value of plan assets at end of year	$	3,373.5	$	2,926.0	$	780.6	$	732.8
Amount recognized in statement of financial position
Other assets	$	—	$	—	$	675.5	$	635.1
Other liabilities		(836.7)		(766.1)		(2.9)		(3.7)
Total	$	(836.7)	$	(766.1)	$	672.6	$	631.4
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	$	760.0	$	737.5	$	(22.8)	$	(17.4)
Prior service benefit		(121.0)		(137.8)		(7.3)		(7.3)
Pre-tax accumulated other comprehensive (income) loss	$	639.0	$	599.7	$	(30.1)	$	(24.7)

Components of Net Periodic Benefit Cost (Income) (Table)

	Pension benefits						Other postretirement benefits
	For the year ended December 31,
	2020		2019		2018		2020		2019		2018
	(in millions)
Service cost	$	72.7	$	66.0	$	73.0	$	—	$	—	$	0.1
Interest cost		117.3		126.5		119.5		2.8		3.7		3.5
Expected return on plan assets		(156.8)		(148.8)		(157.0)		(36.0)		(33.2)		(33.6)
Amortization of prior service benefit		(16.8)		(11.3)		(3.4)		(1.0)		(1.2)		(13.9)
Recognized net actuarial (gain) loss		75.4		70.1		67.8		—		0.1		(1.5)
Net periodic benefit cost (income)	$	91.8	$	102.5	$	99.9	$	(34.2)	$	(30.6)	$	(45.4)

Amounts Recognized in Net Periodic Benefit Cost and Accumulated Other Comprehensive (Income) Loss (Table)

	Pension				Other postretirement
	benefits				benefits
	For the year ended December 31,
	2020		2019		2020		2019
	(in millions)
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	$	97.9	$	134.3	$	(5.4)	$	(57.5)
Prior service (benefit) cost		—		(122.4)		(1.0)		1.7
Amortization of net loss		(75.4)		(70.1)		—		(0.1)
Amortization of prior service benefit		16.8		11.3		1.0		1.2
Total recognized in pre-tax accumulated other comprehensive (income) loss	$	39.3	$	(46.9)	$	(5.4)	$	(54.7)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$	131.1	$	55.6	$	(39.6)	$	(85.3)

Weighted-Average Assumptions Used to Determine Benefit Obligations (Table)

	Pension benefits
	For the year ended December 31,
	2020		2019
Discount rate	2.50	%	3.25	%
Interest crediting rate - cash balance benefit	5.00	%	—	%
Rate of compensation increase:
Cash balance benefit	4.92	%	4.95	%
Traditional benefit	2.96	%	2.98	%
	Other postretirement benefits
	For the year ended December 31,
	2020		2019
Discount rate	2.10	%	2.95	%
Rate of compensation increase	N/A		N/A

Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Table)

	Pension benefits
	For the year ended December 31,
	2020		2019		2018
Discount rate (1)	3.25	%	3.70	%	3.60	%
Expected long-term return on plan assets	5.60	%	5.95	%	6.30	%
Interest crediting rate - cash balance benefit	5.00	%	—	%	—	%
Rate of compensation increase:
Cash balance benefit	4.95	%	4.94	%	4.96	%
Traditional benefit	2.98	%	2.73	%	2.77	%
	Other postretirement benefits
	For the year ended December 31,
	2020		2019		2018
Discount rate (2)	2.95	%	3.95	%	3.35	%
Expected long-term return on plan assets	4.94	%	5.19	%	4.85	%
Rate of compensation increase	N/A		N/A		2.39	%

(1) During the second quarter of 2019, we amended The Principal Pension Plan and The Principal Financial Group Nonqualified Defined Benefit Plan for Employees to end traditional benefit accruals as of December 31, 2022, and begin cash balance accruals January 1, 2023. We remeasured the associated plan assets and pension benefit obligations as of May 31, 2019. A discount rate of 4.15% was used until the remeasurement date at which time a discount rate of 3.70% was used. See "Pension Plan Changes and Plan Gains/Losses" for further details.

(2) During the second quarter 2020, subsidy increases provided under the long-term care plan were capped at 5% per calendar year. This change was remeasured as of March 31, 2020. A discount rate of 2.95% was used until the remeasurement date at which time a discount rate of 2.90% was used.

Assumed Health Care Cost Trend Rates (Table)

	December 31,
	2020		2019
Health care cost trend rate assumed for next year under age 65	6.75	%	6.75	%
Health care cost trend rate assumed for next year age 65 and over	6.00	%	6.00	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.50	%	4.50	%
Year that the rate reaches the ultimate trend rate (under age 65)	2029		2028
Year that the rate reaches the ultimate trend rate (65 and older)	2026		2025

Estimated Future Benefit Payments (Table)

			Other postretirement
			benefits (gross benefit
			payments, including
	Pension benefits		prescription drug benefits)
	(in millions)
Year ending December 31:
2021	$	160.2	$	15.5
2022		159.9		14.8
2023		166.6		13.5
2024		175.8		12.2
2025		179.3		10.9
2026-2030		1,026.0		38.3

Defined Benefit Pension Plans Supplemental Information (Table)

	For the year ended December 31,
	2020						2019
	Qualified		Nonqualified				Qualified		Nonqualified
	Plan		Plan		Total		Plan		Plan		Total
	(in millions)
Amount recognized in statement of financial position
Other assets	$	—	$	—	$	—	$	—	$	—	$	—
Other liabilities		(294.9)		(541.8)		(836.7)		(258.7)		(507.4)		(766.1)
Total	$	(294.9)	$	(541.8)	$	(836.7)	$	(258.7)	$	(507.4)	$	(766.1)
Amount recognized in accumulated other comprehensive loss
Total net actuarial loss	$	563.5	$	196.5	$	760.0	$	567.6	$	169.9	$	737.5
Prior service benefit		(97.8)		(23.2)		(121.0)		(110.3)		(27.5)		(137.8)
Pre-tax accumulated other comprehensive loss	$	465.7	$	173.3	$	639.0	$	457.3	$	142.4	$	599.7
Components of net periodic benefit cost
Service cost	$	66.1	$	6.6	$	72.7	$	59.7	$	6.3	$	66.0
Interest cost		101.2		16.1		117.3		108.0		18.5		126.5
Expected return on plan assets		(156.8)		—		(156.8)		(148.8)		—		(148.8)
Amortization of prior service benefit		(12.6)		(4.2)		(16.8)		(7.8)		(3.5)		(11.3)
Recognized net actuarial loss		59.9		15.5		75.4		57.6		12.5		70.1
Net periodic benefit cost	$	57.8	$	34.0	$	91.8	$	68.7	$	33.8	$	102.5
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial loss	$	55.7	$	42.2	$	97.9	$	80.8	$	53.5	$	134.3
Prior service benefit		—		—		—		(107.2)		(15.2)		(122.4)
Amortization of net loss		(59.8)		(15.6)		(75.4)		(57.6)		(12.5)		(70.1)
Amortization of prior service benefit		12.6		4.2		16.8		7.8		3.5		11.3
Total recognized in pre-tax accumulated other comprehensive (income) loss	$	8.5	$	30.8	$	39.3	$	(76.2)	$	29.3	$	(46.9)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$	66.3	$	64.8	$	131.1	$	(7.5)	$	63.1	$	55.6

Pension benefits

Defined Benefit Plans and Other Postretirement Benefit Plans

Accumulated Benefit Obligation in Excess of Plan Assets (Table)

	December 31,
	2020		2019
	(in millions)
Projected benefit obligation	$	4,210.2	$	3,692.1
Accumulated benefit obligation		4,136.5		3,599.5
Fair value of plan assets		3,373.5		2,926.0

Fair Value of Plan Assets (Table)

	December 31, 2020
	Assets		Amount		Fair value hierarchy level
	measured at		measured at
	fair value		net asset value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Pooled separate account investments:
U.S. large cap equity portfolios (1)	$	712.2	$	—	$	—	$	712.2	$	—
U.S. small/mid cap equity portfolios (2)		121.6		—		—		121.6		—
Balanced asset portfolios (3)		103.7		—		—		103.7		—
International equity portfolios (4)		459.6		—		—		459.6		—
Real estate investment portfolios (5)		195.1						195.1
Single client separate account investments:
Fixed income securities:
U.S. government and agencies		297.5		—		297.5		—		—
States and political subdivisions		28.0		—		—		28.0		—
Corporate		1,223.1		—		—		1,223.1		—
Commercial mortgage-backed securities		13.6		—		—		13.6		—
Other debt obligations		6.4		—		—		6.4		—
Hedge funds (6)		155.8		155.8		—		—		—
Pooled separate account investment (7)		55.1		—		—		55.1		—
Other (8)		1.8		—		—		1.8		—
Total	$	3,373.5	$	155.8	$	297.5	$	2,920.2	$	—

	December 31, 2019
	Assets		Amount		Fair value hierarchy level
	measured at		measured at
	fair value		net asset value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Pooled separate account investments:
U.S. large cap equity portfolios (1)	$	509.7	$	—	$	—	$	509.7	$	—
U.S. small/mid cap equity portfolios (2)		90.9		—		—		90.9		—
Balanced asset portfolios (3)		78.5		—		—		78.5		—
International equity portfolios (4)		328.6		—		—		328.6		—
Real estate investment portfolios (5)		193.5		—		—		193.5		—
Single client separate account investments:
Fixed income securities:
U.S. government and agencies		485.9		—		485.9		—		—
States and political subdivisions		26.1		—		—		26.1		—
Corporate		1,009.1		—		—		1,009.1		—
Commercial mortgage-backed securities		32.7		—		—		32.7		—
Other debt obligations		7.1		—		—		7.1		—
Hedge funds (6)		129.0		129.0		—		—		—
Pooled separate account investment (7)		31.5		—		—		31.5		—
Other (8)		3.4		—		—		3.4		—
Total	$	2,926.0	$	129.0	$	485.9	$	2,311.1	$	—

(1) The portfolios invest primarily in publicly traded equity securities of large U.S. companies.

(2) The portfolios invest primarily in publicly traded equity securities of mid-sized and small U.S. companies.

(3) The portfolios are a combination of underlying fixed income and equity investment options. These investment options may include balanced, asset allocation, target-date and target-risk investment options. Although typically lower risk than investment options that invest solely in equities, all investment options in this category have the potential to lose value.

(4) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies.

(5) The portfolio invests primarily in U.S. commercial real estate properties through a separate account.

(6) The hedge funds have varying investment strategies that also have a variety of redemption terms and conditions. We do not have unfunded commitments associated with these hedge funds.

(7) The single client separate accounts invest in a money market pooled separate account.

(8) Includes cash and net (payables)/receivables for the single client separate accounts.

Target Asset Allocation (Table)

Asset category	Target allocation
Fixed income security portfolios	25	%	-	80	%
Equity portfolios	5	%	-	60	%
Real estate investment portfolios				10	%
Alternatives				5	%

Other postretirement benefits

Defined Benefit Plans and Other Postretirement Benefit Plans

Accumulated Benefit Obligation in Excess of Plan Assets (Table)

	December 31,
	2020		2019
	(in millions)
Accumulated postretirement benefit obligation	$	2.9	$	3.8
Fair value of plan assets		—		—

Fair Value of Plan Assets (Table)

	December 31, 2020
	Assets		Fair value hierarchy level
	measured at
	fair value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Cash and cash equivalents	$	0.5	$	0.5	$	—	$	—
Fixed income security portfolios:
Fixed income investment funds (1)		625.2		605.9		19.3		—
U.S. equity portfolios (2)		103.5		38.2		65.3		—
International equity portfolios (3)		51.4		18.4		33.0		—
Total	$	780.6	$	663.0	$	117.6	$	—

	December 31, 2019
	Assets		Fair value hierarchy level
	measured at
	fair value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Cash and cash equivalents	$	0.6	$	0.6	$	—	$	—
Fixed income security portfolios:
Fixed income investment funds (1)		370.5		331.0		39.5		—
U.S. equity portfolios (2)		254.5		210.3		44.2		—
International equity portfolios (3)		107.2		88.9		18.3		—
Total	$	732.8	$	630.8	$	102.0	$	—

(1) The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations.

(2) The portfolios invest primarily in publicly traded equity securities of large U.S. companies.

(3) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies.

Target Asset Allocation (Table)

Asset category	Target allocation
U.S. equity portfolios	35	%
International equity portfolios	15	%
Fixed income security portfolios	50	%