Employee and Agent Benefits (Tables)

12 Months Ended

Dec. 31, 2015

Defined Benefit Plans and Other Postretirement Benefit Plans

Obligations and Funded Status (Table)

	Pension benefits						Other postretirement benefits
	December 31,						December 31,
	2015			2014			2015			2014
	(in millions)
Change in benefit obligation
Benefit obligation at beginning of year	$	(3,060.0	)	$	(2,440.2	)	$	(169.7	)	$	(140.6	)
Service cost		(63.2	)		(54.0	)		(2.0	)		(1.4	)
Interest cost		(120.3	)		(117.1	)		(6.6	)		(6.6	)
Actuarial gain (loss)		96.3			(532.9	)		(2.7	)		(26.0	)
Participant contribution		—			—			(6.4	)		(6.6	)
Benefits paid		95.0			84.2			12.7			12.2
Other		—			—			9.0			(0.7	)
Benefit obligation at end of year	$	(3,052.2	)	$	(3,060.0	)	$	(165.7	)	$	(169.7	)
Change in plan assets
Fair value of plan assets at beginning of year	$	2,218.3		$	1,925.6		$	639.7		$	613.0
Actual return on plan assets		(50.0	)		246.0			(6.9	)		31.9
Employer contribution		93.0			130.9			0.5			0.4
Participant contributions		—			—			6.4			6.6
Benefits paid		(95.0	)		(84.2	)		(12.7	)		(12.2	)
Fair value of plan assets at end of year	$	2,166.3		$	2,218.3		$	627.0		$	639.7
Amount recognized in statement of financial position
Other assets	$	—		$	—		$	461.9		$	470.7
Other liabilities		(885.9	)		(841.7	)		(0.6	)		(0.7	)
Total	$	(885.9	)	$	(841.7	)	$	461.3		$	470.0
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	$	771.2		$	759.2		$	(8.6	)	$	(53.0	)
Prior service benefit		(5.1	)		(6.9	)		(33.0	)		(35.9	)
Pre-tax accumulated other comprehensive (income) loss	$	766.1		$	752.3		$	(41.6	)	$	(88.9	)

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

	Pension benefits									Other postretirement benefits
	For the year ended December 31,
	2015			2014			2013			2015			2014			2013
	(in millions)
Service cost	$	63.2		$	54.0		$	57.1		$	2.0		$	1.4		$	1.0
Interest cost		120.3			117.1			103.8			6.6			6.6			5.7
Expected return on plan assets		(160.6	)		(131.9	)		(127.4	)		(33.9	)		(32.6	)		(28.8	)
Amortization of prior service benefit		(1.9	)		(4.7	)		(8.7	)		(18.5	)		(20.3	)		(25.9	)
Recognized net actuarial (gain) loss		102.4			50.5			118.5			(0.8	)		(3.4	)		1.0
Other		—			—			—			5.8			—			—
Net periodic benefit cost (income)	$	123.4		$	85.0		$	143.3		$	(38.8	)	$	(48.3	)	$	(47.0	)

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

	Pension benefits						Other postretirement benefits
	For the year ended December 31,
	2015			2014			2015			2014
	(in millions)
Other changes recognized in accumulated other comprehensive loss
Net actuarial loss	$	114.3		$	418.8		$	43.5		$	26.7
Amortization of gain (loss)		(102.4	)		(50.5	)		0.8			3.4
Amortization of prior service benefit		1.9			4.7			18.5			20.3
Plan changes		—			—			(15.5	)		—
Total recognized in pre-tax accumulated other comprehensive loss	$	13.8		$	373.0		$	47.3		$	50.4
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive loss	$	137.2		$	458.0		$	8.5		$	2.1

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

	Pension benefits
	For the year ended December 31,
	2015			2014
Discount rate		4.50	%		4.00	%
Rate of compensation increase:
Traditional benefit		2.98	%		3.02	%

	Other postretirement benefits
	For the year ended December 31,
	2015			2014
Discount rate		4.15	%		4.00	%
Rate of compensation increase		4.82	%		4.82	%

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

	Pension benefits
	For the year ended December 31,
	2015			2014			2013
Discount rate		4.00	%		4.90	%		4.00	%
Expected long-term return on plan assets		7.20	%		6.75	%		7.50	%
Rate of compensation increase:
Cash balance benefit		5.25	%		5.29	%		5.29	%
Traditional benefit		3.02	%		3.06	%		3.06	%

	Other postretirement benefits
	For the year ended December 31,
	2015			2014			2013
Discount rate		4.00	%		4.90	%		4.00	%
Expected long-term return on plan assets		5.36	%		5.36	%		5.62	%
Rate of compensation increase		4.82	%		4.83	%		4.83	%

Assumed Health Care Cost Trend Rates (Table)

	December 31,
	2015			2014
Health care cost trend rate assumed for next year under age 65		7.0	%		7.0	%
Health care cost trend rate assumed for next year age 65 and over		6.0	%		6.0	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.5	%		4.5	%
Year that the rate reaches the ultimate trend rate (under age 65)		2023			2019
Year that the rate reaches the ultimate trend rate (65 and older)		2021			2020

Effects of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Table)

	1-percentage point increase			1-percentage point decrease
	(in millions)
Effect on total of service cost and interest cost components	$	0.6		$	(0.5	)
Effect on accumulated postretirement benefit obligation		(7.1	)		6.5

Estimated Future Benefit Payments (Table)

	Pension benefits		Other postretirement benefits (gross benefit payments, including prescription drug benefits)		Amount of Medicare Part D subsidy receipts
	(in millions)
Year ending December 31:
2016	$	110.0	$	14.3	$	0.2
2017		117.9		14.4		0.1
2018		127.9		14.5		0.2
2019		131.5		14.9		0.1
2020		141.9		15.2		0.1
2021 - 2025		842.4		83.9		0.4

Defined Benefit Pension Plans Supplemental Information (Table)

	For the year ended December 31,
	2015									2014
	Qualified Plan			Nonqualified Plan			Total			Qualified Plan			Nonqualified Plan			Total
	(in millions)
Amount recognized in statement of financial position
Other assets	$	—		$	—		$	—		$	—		$	—		$	—
Other liabilities		(453.0	)		(432.9	)		(885.9	)		(385.3	)		(456.4	)		(841.7	)
Total	$	(453.0	)	$	(432.9	)	$	(885.9	)	$	(385.3	)	$	(456.4	)	$	(841.7	)
Amount recognized in accumulated other comprehensive loss
Total net actuarial loss	$	659.0		$	112.2		$	771.2		$	603.1		$	156.1		$	759.2
Prior service benefit		(2.6	)		(2.5	)		(5.1	)		(3.4	)		(3.5	)		(6.9	)
Pre-tax accumulated other comprehensive loss	$	656.4		$	109.7		$	766.1		$	599.7		$	152.6		$	752.3
Components of net periodic benefit cost
Service cost	$	54.8		$	8.4		$	63.2		$	46.8		$	7.2		$	54.0
Interest cost		102.3			18.0			120.3			99.1			18.0			117.1
Expected return on plan assets		(160.6	)		—			(160.6	)		(131.9	)		—			(131.9	)
Amortization of prior service benefit		(0.8	)		(1.1	)		(1.9	)		(3.1	)		(1.6	)		(4.7	)
Recognized net actuarial loss		86.3			16.1			102.4			42.9			7.6			50.5
Net periodic benefit cost	$	82.0		$	41.4		$	123.4		$	53.8		$	31.2		$	85.0
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	$	142.1		$	(27.8	)	$	114.3		$	347.8		$	71.0		$	418.8
Amortization of net loss		(86.3	)		(16.1	)		(102.4	)		(42.9	)		(7.6	)		(50.5	)
Amortization of prior service benefit		0.8			1.1			1.9			3.1			1.6			4.7
Total recognized in pre-tax accumulated other comprehensive (income) loss	$	56.6		$	(42.8	)	$	13.8		$	308.0		$	65.0		$	373.0
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$	138.6		$	(1.4	)	$	137.2		$	361.8		$	96.2		$	458.0

Pension benefits

Defined Benefit Plans and Other Postretirement Benefit Plans

Accumulated Benefit Obligation in Excess of Plan Assets (Table)

	December 31,
	2015		2014
	(in millions)
Projected benefit obligation	$	3,052.2	$	3,060.0
Accumulated benefit obligation		2,799.2		2,854.0
Fair value of plan assets		2,166.3		2,218.3

Fair Value of Plan Assets (Table)

	December 31, 2015
			Fair value hierarchy level
	Assets measured at fair value
			Level 1		Level 2		Level 3
	(in millions)
Asset category
U.S. large cap equity portfolios (1)	$	591.2	$	—	$	591.2	$	—
U.S. small/mid cap equity portfolios (2)		138.0		—		138.0		—
Balanced asset portfolios (3)		119.9		—		119.9		—
International equity portfolios (4)		201.7		—		201.7		—
Fixed income security portfolios (5)		997.0		—		997.0		—
Real estate investment portfolios:
Direct real estate investments (6)		118.5		—		118.5		—
Total	$	2,166.3	$	—	$	2,166.3	$	—

	December 31, 2014
			Fair value hierarchy level
	Assets measured at fair value
			Level 1		Level 2		Level 3
	(in millions)
Asset category
U.S. large cap equity portfolios (1)	$	493.7	$	—	$	493.7	$	—
U.S. small/mid cap equity portfolios (2)		118.1		—		118.1		—
Balanced asset portfolios (3)		114.2		—		114.2		—
International equity portfolios (4)		174.8		—		174.8		—
Fixed income security portfolios (5)		1,213.2		—		1,213.2		—
Real estate investment portfolios:
Direct real estate investments (6)		104.3		—		104.3		—
Total	$	2,218.3	$	—	$	2,218.3	$	—

(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 portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations.
(6)	The portfolio invests primarily in U.S. commercial real estate properties through a separate account.

Target Asset Allocation (Table)

Asset Category	Target allocation
U.S. equity portfolios	0% - 45%
International equity portfolios	0% - 15%
Fixed income security portfolios	30% - 100%
Real estate investment portfolios	0% - 10%

Other postretirement benefits

Defined Benefit Plans and Other Postretirement Benefit Plans

Accumulated Benefit Obligation in Excess of Plan Assets (Table)

	December 31,
	2015		2014
	(in millions)
Accumulated postretirement benefit obligation	$	1.3	$	1.5
Fair value of plan assets		0.7		0.8

Fair Value of Plan Assets (Table)

	December 31, 2015
			Fair value hierarchy level
	Assets measured at fair value
			Level 1		Level 2		Level 3
	(in millions)
Asset category
Cash and cash equivalents	$	5.9	$	5.9	$	—	$	—
Fixed income security portfolios:
Fixed income investment funds (1)		181.7		173.2		8.5		—
Principal Life general account investment (2)		33.5		—		—		33.5
U.S. equity portfolios (3)		339.6		278.8		60.8		—
International equity portfolios (4)		66.3		54.4		11.9		—
Total	$	627.0	$	512.3	$	81.2	$	33.5

	December 31, 2014
			Fair value hierarchy level
	Assets measured at fair value
			Level 1		Level 2		Level 3
	(in millions)
Asset category
Cash and cash equivalents	$	5.5	$	5.5	$	—	$	—
Fixed income security portfolios:
Fixed income investment funds (1)		164.4		161.1		3.3		—
Principal Life general account investment (2)		36.3		—		—		36.3
U.S. equity portfolios (3)		375.6		311.0		64.6		—
International equity portfolios (4)		57.9		44.5		13.4		—
Total	$	639.7	$	522.1	$	81.3	$	36.3

(1)	The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations.
(2)	The general account is invested in various fixed income securities.
(3)	The portfolios invest primarily in publicly traded equity securities of large U.S. companies.
(4)	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		45	%
International equity portfolios		30	%
Fixed income security portfolios		25	%

Reconciliation of Plan Assets Measured at Fair Value Using Significant Unobservable Inputs (Table)

	For the year ended December 31, 2015
			Actual return gains (losses) on plan assets
														Ending asset balance as of December 31, 2015
	Beginning asset balance as of December 31, 2014		Relating to assets still held at the reporting date		Relating to assets sold during the period		Net purchases, sales, and settlements			Transfers into Level 3		Transfers out of Level 3
	(in millions)
Asset category
Principal Life general account investment	$	36.3	$	0.2	$	—	$	(3.0	)	$	—	$	—	$	33.5

	For the year ended December 31, 2014
			Actual return gains (losses) on plan assets
														Ending assets balance as of December 31, 2014
	Beginning assets balance as of December 31, 2013		Relating to assets still held at the reporting date		Relating to assets sold during the period		Net purchases, sales, and settlements			Transfers into Level 3		Transfers out of Level 3
	(in millions)
Asset category
Principal Life general account investment	$	38.8	$	0.8	$	—	$	(3.3	)	$	—	$	—	$	36.3

	For the year ended December 31, 2013
			Actual return gains (losses) on plan assets
														Ending assets balance as of December 31, 2013
	Beginning assets balance as of December 31, 2012		Relating to assets still held at the reporting date		Relating to assets sold during the period		Net purchases, sales, and settlements			Transfers into Level 3		Transfers out of Level 3
	(in millions)
Asset category
Principal Life general account investment	$	42.1	$	1.1	$	—	$	(4.4	)	$	—	$	—	$	38.8