Nature of Operations and Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2015

Nature of Operations and Significant Accounting Policies

Cash and Cash Equivalents - Policy

Cash and Cash Equivalents

        Cash and cash equivalents include cash on hand, money market instruments and other debt issues with a maturity date of three months or less when purchased.

Investments - Policy

Investments

        Fixed maturities include bonds, asset-backed securities ("ABS"), redeemable preferred stock and certain nonredeemable preferred securities. Equity securities include mutual funds, common stock, nonredeemable preferred stock and required regulatory investments. We classify fixed maturities and equity securities as either available-for-sale or trading at the time of the purchase and, accordingly, carry them at fair value. See Note 14, Fair Value Measurements, for methodologies related to the determination of fair value. Unrealized gains and losses related to available-for-sale securities, excluding those in fair value hedging relationships, are reflected in stockholders' equity, net of adjustments associated with DAC and related actuarial balances, derivatives in cash flow hedge relationships and applicable income taxes. Unrealized gains and losses related to hedged portions of available-for-sale securities in fair value hedging relationships and mark-to-market adjustments on certain trading securities are reflected in net realized capital gains (losses). Mark-to-market adjustments related to certain securities carried at fair value with an investment objective to realize economic value through mark-to-market changes are reflected in net investment income.

        The cost of fixed maturities is adjusted for amortization of premiums and accrual of discounts, both computed using the interest method. The cost of fixed maturities and equity securities classified as available-for-sale is adjusted for declines in value that are other than temporary. Impairments in value deemed to be other than temporary are primarily reported in net income as a component of net realized capital gains (losses), with noncredit impairment losses for certain fixed maturities, available-for-sale reported in other comprehensive income ("OCI"). Interest income, as well as prepayment fees and the amortization of the related premium or discount, is reported in net investment income. For loan-backed and structured securities, we recognize income using a constant effective yield based on currently anticipated cash flows.

        Real estate investments are reported at cost less accumulated depreciation. The initial cost basis of properties acquired through loan foreclosures are the lower of the fair market values of the properties at the time of foreclosure or the outstanding loan balance. Buildings and land improvements are generally depreciated on the straight-line method over the estimated useful life of improvements and tenant improvement costs are depreciated on the straight-line method over the term of the related lease. We recognize impairment losses for properties when indicators of impairment are present and a property's expected undiscounted cash flows are not sufficient to recover the property's carrying value. In such cases, the cost basis of the properties are reduced to fair value. Real estate expected to be disposed is carried at the lower of cost or fair value, less cost to sell, with valuation allowances established accordingly and depreciation no longer recognized. The carrying amount of real estate held for sale was $169.7 million and $174.0 million as of December 31, 2015 and 2014, respectively. Any impairment losses and any changes in valuation allowances are reported in net income.

        Commercial and residential mortgage loans are generally reported at cost adjusted for amortization of premiums and accrual of discounts, computed using the interest method, net of valuation allowances. Interest income is accrued on the principal amount of the loan based on the loan's contractual interest rate. Interest income, as well as prepayment of fees and the amortization of the related premium or discount, is reported in net investment income. Any changes in the valuation allowances are reported in net income as net realized capital gains (losses). We measure impairment based upon the difference between carrying value and estimated value less cost to sell. Estimated value is based on either the present value of expected cash flows discounted at the loan's effective interest rate, the loan's observable market price or the fair value of the collateral. If foreclosure is probable, the measurement of any valuation allowance is based upon the fair value of the collateral.

        Net realized capital gains and losses on sales of investments are determined on the basis of specific identification. In general, in addition to realized capital gains and losses on investment sales and periodic settlements on derivatives not designated as hedges, we report gains and losses related to the following in net realized capital gains (losses): other-than-temporary impairments of securities and subsequent realized recoveries, mark-to-market adjustments on certain trading securities, mark-to-market adjustments on certain seed money investments, fair value hedge and cash flow hedge ineffectiveness, mark-to-market adjustments on derivatives not designated as hedges, changes in the mortgage loan valuation allowance provision, impairments of real estate held for investment and impairments on equity method investments. Investment gains and losses on sales of certain real estate held for sale due to investment strategy and mark-to-market adjustments on certain securities carried at fair value with an investment objective to realize economic value through mark-to-market changes are reported as net investment income and are excluded from net realized capital gains (losses).

        Policy loans and other investments are primarily reported at cost, excluding seed money investments, other investment funds, derivative assets, commercial mortgage loans of consolidated VIEs for which the fair value option was elected and equity method real estate investments for which the fair value option was elected.

Derivatives - Policy

Derivatives

        Overview.    Derivatives are financial instruments whose values are derived from interest rates, foreign exchange rates, financial indices or the values of securities. Derivatives generally used by us include interest rate swaps, interest rate options, swaptions, currency swaps, currency forwards, equity options, futures, credit default swaps and total return swaps. Derivatives may be exchange traded, cleared through centralized clearinghouses, or contracted in the over-the-counter market without being cleared. Derivative positions are either assets or liabilities in the consolidated statements of financial position and are measured at fair value, generally by obtaining quoted market prices or through the use of pricing models. See Note 14, Fair Value Measurements, for policies related to the determination of fair value. Fair values can be affected by changes in interest rates, foreign exchange rates, financial indices, values of securities, credit spreads, and market volatility and liquidity.

        Accounting and Financial Statement Presentation.    We designate derivatives as either:

(a)	a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, including those denominated in a foreign currency ("fair value hedge");
(b)	a hedge of a forecasted transaction or the exposure to variability of cash flows to be received or paid related to a recognized asset or liability, including those denominated in a foreign currency ("cash flow hedge");
(c)	a hedge of a net investment in a foreign operation or
(d)	a derivative not designated as a hedging instrument.

        Our accounting for the ongoing changes in fair value of a derivative depends on the intended use of the derivative and the designation, as described above, and is determined when the derivative contract is entered into or at the time of redesignation. Hedge accounting is used for derivatives that are specifically designated in advance as hedges and that reduce our exposure to an indicated risk by having a high correlation between changes in the value of the derivatives and the items being hedged at both the inception of the hedge and throughout the hedge period.

        Fair Value Hedges.    When a derivative is designated as a fair value hedge and is determined to be highly effective, changes in its fair value, along with changes in the fair value of the hedged asset, liability or firm commitment attributable to the hedged risk, are reported in net realized capital gains (losses). Any difference between the net change in fair value of the derivative and the hedged item represents hedge ineffectiveness.

        Cash Flow Hedges.    When a derivative is designated as a cash flow hedge and is determined to be highly effective, changes in its fair value are recorded as a component of OCI. Any hedge ineffectiveness is recorded immediately in net income. At the time the variability of cash flows being hedged impacts net income, the related portion of deferred gains or losses on the derivative instrument is reclassified and reported in net income.

        Net Investment in a Foreign Operation Hedge.    When a derivative is used as a hedge of a net investment in a foreign operation, its change in fair value, to the extent effective as a hedge, is recorded as a component of OCI. Any hedge ineffectiveness is recorded immediately in net income. If the foreign operation is sold or upon complete or substantially complete liquidation, the deferred gains or losses on the derivative instrument are reclassified into net income.

        Non-Hedge Derivatives.    If a derivative does not qualify or is not designated for hedge accounting, all changes in fair value are reported in net income without considering the changes in the fair value of the economically associated assets or liabilities.

        Hedge Documentation and Effectiveness Testing.    At inception, we formally document all relationships between hedging instruments and hedged items, as well as our risk management objective and strategy for undertaking various hedge transactions. This process includes associating all derivatives designated as fair value or cash flow hedges with specific assets or liabilities on the statement of financial position or with specific firm commitments or forecasted transactions. Effectiveness of the hedge is formally assessed at inception and throughout the life of the hedging relationship. Even if a derivative is highly effective and qualifies for hedge accounting treatment, the hedge might have some ineffectiveness.

        We use qualitative and quantitative methods to assess hedge effectiveness. Qualitative methods may include monitoring changes to terms and conditions and counterparty credit ratings. Quantitative methods may include statistical tests including regression analysis and minimum variance and dollar offset techniques.

        Termination of Hedge Accounting.    We prospectively discontinue hedge accounting when (1) the criteria to qualify for hedge accounting is no longer met, e.g., a derivative is determined to no longer be highly effective in offsetting the change in fair value or cash flows of a hedged item; (2) the derivative expires, is sold, terminated or exercised or (3) we remove the designation of the derivative being the hedging instrument for a fair value or cash flow hedge.

        If it is determined that a derivative no longer qualifies as an effective hedge, the derivative will continue to be carried on the consolidated statements of financial position at its fair value, with changes in fair value recognized prospectively in net realized capital gains (losses). The asset or liability under a fair value hedge will no longer be adjusted for changes in fair value pursuant to hedging rules and the existing basis adjustment is amortized to the consolidated statements of operations line associated with the asset or liability. The component of AOCI related to discontinued cash flow hedges that are no longer highly effective is amortized to the consolidated statements of operations consistent with the net income impacts of the original hedged cash flows. If a cash flow hedge is discontinued because it is probable the hedged forecasted transaction will not occur, the deferred gain or loss is immediately reclassified from AOCI into net income.

        Embedded Derivatives.    We purchase and issue certain financial instruments and products that contain a derivative that is embedded in the financial instrument or product. We assess whether this embedded derivative is clearly and closely related to the asset or liability that serves as its host contract. If we deem that the embedded derivative's terms are not clearly and closely related to the host contract, and a separate instrument with the same terms would qualify as a derivative instrument, the derivative is bifurcated from that contract and held at fair value on the consolidated statements of financial position, with changes in fair value reported in net income.

Contractholder and Policyholder Liabilities - Policy

Contractholder and Policyholder Liabilities

        Contractholder and policyholder liabilities (contractholder funds, future policy benefits and claims and other policyholder funds) include reserves for investment contracts and reserves for universal life, term life insurance, participating traditional individual life insurance, group life insurance, health insurance and disability income policies, as well as a provision for dividends on participating policies.

        Investment contracts are contractholders' funds on deposit with us and generally include reserves for pension and annuity contracts. Reserves on investment contracts are equal to the cumulative deposits less any applicable charges and withdrawals plus credited interest. Reserves for universal life insurance contracts are equal to cumulative deposits less charges plus credited interest, which represents the account balances that accrue to the benefit of the policyholders.

        We hold additional reserves on certain long duration contracts where benefit features result in gains in early years followed by losses in later years, universal life/variable universal life contracts that contain no lapse guarantee features, or annuities with guaranteed minimum death benefits.

        Reserves for nonparticipating term life insurance and disability income contracts are computed on a basis of assumed investment yield, mortality, morbidity and expenses, including a provision for adverse deviation, which generally varies by plan, year of issue and policy duration. Investment yield is based on our experience. Mortality, morbidity and withdrawal rate assumptions are based on our experience and are periodically reviewed against both industry standards and experience.

        Reserves for participating life insurance contracts are based on the net level premium reserve for death and endowment policy benefits. This net level premium reserve is calculated based on dividend fund interest rates and mortality rates guaranteed in calculating the cash surrender values described in the contract.

        Participating business represented approximately 9%, 11% and 12% of our life insurance in force and 36%, 40% and 43% of the number of life insurance policies in force at December 31, 2015, 2014 and 2013, respectively. Participating business represented approximately 36%, 40% and 40% of life insurance premiums for the years ended December 31, 2015, 2014 and 2013, respectively. The amount of dividends to policyholders is declared annually by Principal Life's Board of Directors. The amount of dividends to be paid to policyholders is determined after consideration of several factors including interest, mortality, morbidity and other expense experience for the year and judgment as to the appropriate level of statutory surplus to be retained by Principal Life. At the end of the reporting period, Principal Life establishes a dividend liability for the pro rata portion of the dividends expected to be paid on or before the next policy anniversary date.

        Some of our policies and contracts require payment of fees or other policyholder assessments in advance for services that will be rendered over the estimated lives of the policies and contracts. These payments are established as unearned revenue liabilities upon receipt and included in other policyholder funds in the consolidated statements of financial position. These unearned revenue reserves are amortized to operations over the estimated lives of these policies and contracts in relation to the emergence of estimated gross profits ("EGPs").

        The liability for unpaid disability and health claims is an estimate of the ultimate net cost of reported and unreported losses not yet settled. This liability is estimated using actuarial analyses and case basis evaluations. Although considerable variability is inherent in such estimates, we believe that the liability for unpaid claims is adequate. These estimates are continually reviewed and, as adjustments to this liability become necessary, such adjustments are reflected in net income.

Recognition of Premiums and Other Considerations, Fees and Other Revenues and Benefits - Policy

Recognition of Premiums and Other Considerations, Fees and Other Revenues and Benefits

        Traditional individual life insurance products include those products with fixed and guaranteed premiums and benefits and consist principally of whole life and term life insurance policies. Premiums from these products are recognized as premium revenue when due. Related policy benefits and expenses for individual life products are associated with earned premiums and result in the recognition of profits over the expected term of the policies and contracts.

        Immediate annuities with life contingencies include products with fixed and guaranteed annuity considerations and benefits and consist principally of group and individual single premium annuities with life contingencies. Annuity considerations from these products are recognized as premium revenue. However, the collection of these annuity considerations does not represent the completion of the earnings process, as we establish annuity reserves, using estimates for mortality and investment assumptions, which include provision for adverse deviation as required by U.S. GAAP. We anticipate profits to emerge over the life of the annuity products as we earn investment income, pay benefits and release reserves.

        Group life and health insurance premiums are generally recorded as premium revenue over the term of the coverage. Certain group contracts contain experience premium refund provisions based on a pre-defined formula that reflects their claim experience. Experience premium refunds reduce revenue over the term of the coverage and are adjusted to reflect current experience. Related policy benefits and expenses for group life and health insurance products are associated with earned premiums and result in the recognition of profits over the term of the policies and contracts. Fees for contracts providing claim processing or other administrative services are recorded as revenue over the period the service is provided.

        Universal life-type policies are insurance contracts with terms that are not fixed. Amounts received as payments for such contracts are not reported as premium revenues. Revenues for universal life-type insurance contracts consist of policy charges for the cost of insurance, policy initiation and administration, surrender charges and other fees that have been assessed against policy account values and investment income. Policy benefits and claims that are charged to expense include interest credited to contracts and benefit claims incurred in the period in excess of related policy account balances.

        Investment contracts do not subject us to significant risks arising from policyholder mortality or morbidity and consist primarily of guaranteed investment contracts ("GICs"), funding agreements and certain deferred annuities. Amounts received as payments for investment contracts are established as investment contract liability balances and are not reported as premium revenues. Revenues for investment contracts consist of investment income and policy administration charges. Investment contract benefits that are charged to expense include benefit claims incurred in the period in excess of related investment contract liability balances and interest credited to investment contract liability balances.

        Fees and other revenues are earned for asset management services provided to retail and institutional clients based largely upon contractual rates applied to the market value of the client's portfolio. Additionally, fees and other revenues are earned for administrative services performed including recordkeeping and reporting services for retirement savings plans. Fees and other revenues received for performance of asset management and administrative services are recognized as revenue when earned, typically when the service is performed.

        Fees for managing customers' mandatory retirement savings accounts in Chile are collected with each monthly deposit made by our customers. If a customer stops contributing before retirement age, we collect no fees but services are still provided. We recognize revenue from these long-term service contracts as services are performed over the life of the contract.

Deferred Acquisition Costs - Policy

Deferred Acquisition Costs

        Incremental direct costs of contract acquisition as well as certain costs directly related to acquisition activities (underwriting, policy issuance and processing, medical and inspection and sales force contract selling) for the successful acquisition of new and renewal insurance policies and investment contract business are capitalized to the extent recoverable. Commissions and other incremental direct costs for the acquisition of long-term service contracts are also capitalized to the extent recoverable. Maintenance costs and acquisition costs that are not deferrable are charged to operations as incurred.

        DAC for universal life-type insurance contracts and certain investment contracts are being amortized over the lives of the policies and contracts in relation to the emergence of EGPs or, in certain circumstances, estimated gross revenues. This amortization is adjusted in the current period when EGPs or estimated gross revenues are revised. For individual variable universal life insurance, individual variable annuities and group annuities that have separate account U.S. equity investment options, we utilize a mean reversion method (reversion to the mean assumption), a common industry practice, to determine the future domestic equity market growth assumption used for the amortization of DAC. The DAC on participating life insurance policies are being amortized in proportion to estimated gross margins. The DAC on nonparticipating term life insurance and individual disability policies are being amortized over the premium-paying period of the related policies using assumptions consistent with those used in computing policyholder liabilities.

        DAC on insurance policies and investment contracts are subject to recoverability testing at the time of policy issue and loss recognition testing on an annual basis, or when an event occurs that may warrant loss recognition. If loss recognition is necessary, DAC would be written off to the extent that it is determined that future policy premiums and investment income or gross profits are not adequate to cover related losses and expenses.

        DAC on long-term service contracts are amortized in proportion to the revenue recognized or straight-line if no pattern of revenue recognition can be reasonably predicted. We amortize capitalized costs of long-term service contracts on a straight-line basis over the expected contract life.

Deferred Acquisition Costs on Internal Replacements - Policy

Deferred Acquisition Costs on Internal Replacements

        All insurance and investment contract modifications and replacements are reviewed to determine if the internal replacement results in a substantially changed contract. If so, the acquisition costs, sales inducements and unearned revenue associated with the new contract are deferred and amortized over the lifetime of the new contract. In addition, the existing DAC, sales inducement costs and unearned revenue balances associated with the replaced contract are written off. If an internal replacement results in a substantially unchanged contract, the acquisition costs, sales inducements and unearned revenue associated with the new contract are immediately recognized in the period incurred. In addition, the existing DAC, sales inducement costs or unearned revenue balance associated with the replaced contract is not written off, but instead is carried over to the new contract.

Long-Term Debt - Policy

Long-Term Debt

        Long-term debt includes notes payable, nonrecourse mortgages and other debt with a maturity date greater than one year at the date of issuance. Current maturities of long-term debt are classified as long-term debt in our statement of financial position.

Reinsurance - Policy

Reinsurance

        We enter into reinsurance agreements with other companies in the normal course of business in order to limit losses and minimize exposure to significant risks. We may assume reinsurance from or cede reinsurance to other companies. Assets and liabilities related to reinsurance ceded are reported on a gross basis. Premiums and expenses are reported net of reinsurance ceded. The cost of reinsurance related to long-duration contracts is accounted for over the life of the underlying reinsured policies using assumptions consistent with those used to account for the underlying policies. We are contingently liable with respect to reinsurance ceded to other companies in the event the reinsurer is unable to meet the obligations it has assumed. At December 31, 2015 and 2014, we had $397.5 million and $338.0 million of net ceded reinsurance recoverables related to claims that have been received, respectively. At December 31, 2015 and 2014, our largest exposures to a single third party reinsurer was in our life insurance business, which totaled $40.6 billion and $38.9 billion of life insurance in force, representing 15% and 16% of total net life insurance in force, respectively. The reinsurance recoverable relating to claims received that are associated to this single third party reinsurer recorded in our consolidated statements of financial position was $58.9 million and $48.1 million at December 31, 2015 and 2014, respectively.

        The effects of reinsurance on premiums and other considerations and policy and contract benefits were as follows:

	For the year ended December 31,
	2015			2014			2013
	(in millions)
Premiums and other considerations:
Direct	$	5,710.8		$	4,123.7		$	3,524.8
Assumed		1.9			2.1			2.5
Ceded		(402.4	)		(402.9	)		(373.2	)
Net premiums and other considerations	$	5,310.3		$	3,722.9		$	3,154.1
Benefits, claims and settlement expenses:
Direct	$	7,196.7		$	5,532.5		$	4,933.3
Assumed		28.7			30.7			32.2
Ceded		(527.7	)		(332.2	)		(281.9	)
Net benefits, claims and settlement expenses	$	6,697.7		$	5,231.0		$	4,683.6

Separate Accounts - Policy

Separate Accounts

        The separate accounts are legally segregated and are not subject to the claims that arise out of any of our other business. The client, rather than us, directs the investments and bears the investment risk of these funds. The separate account assets represent the fair value of funds that are separately administered by us for contracts with equity, real estate and fixed income investments and are presented as a summary total within the consolidated statements of financial position. An equivalent amount is reported as separate account liabilities, which represent the obligation to return the monies to the client. We receive fees for mortality, withdrawal and expense risks, as well as administrative, maintenance and investment advisory services that are included in the consolidated statement of operations. Net deposits, net investment income and realized and unrealized capital gains and losses of the separate accounts are not reflected in the consolidated statements of operations.

        Separate account assets and separate account liabilities include certain international retirement accumulation products where the segregated funds and associated obligation to the client are consolidated within our financial statements. We have determined that summary totals are the most meaningful presentation for these funds.

        At December 31, 2015 and December 31, 2014, the separate accounts include a separate account valued at $158.2 million and $205.4 million, respectively, which primarily includes shares of our stock that were allocated and issued to eligible participants of qualified employee benefit plans administered by us as part of the policy credits issued under our 2001 demutualization. These shares are included in both basic and diluted earnings per share calculations. In the consolidated statements of financial position, the separate account shares are recorded at fair value and are reported as separate account assets with a corresponding separate account liability to eligible participants of the qualified plan. Changes in fair value of the separate account shares are reflected in both the separate account assets and separate account liabilities and do not impact our results of operations.

Income Taxes - Policy

Income Taxes

        We file a U.S. consolidated income tax return that includes all of our qualifying subsidiaries. In addition, we file income tax returns in all states and foreign jurisdictions in which we conduct business. Our policy of allocating income tax expenses and benefits to companies in the group is generally based upon pro rata contribution of taxable income or operating losses. We are taxed at corporate rates on taxable income based on existing tax laws. Current income taxes are charged or credited to net income based upon amounts estimated to be payable or recoverable as a result of taxable operations for the current year. Deferred income taxes are provided for the tax effect of temporary differences in the financial reporting and income tax bases of assets and liabilities and net operating losses using enacted income tax rates and laws. The effect on deferred income tax assets and deferred income tax liabilities of a change in tax rates is recognized in operations in the period in which the change is enacted.

Foreign Exchange - Policy

Foreign Exchange

        Assets and liabilities of our foreign subsidiaries and affiliates denominated in non-U.S. dollars, where the U.S. dollar is not the functional currency, are translated into U.S. dollar equivalents at the year-end spot foreign exchange rates. Resulting translation adjustments are reported as a component of stockholders' equity, along with any related hedge and tax effects. Revenues and expenses for these entities are translated at the average exchange rates. Revenue, expense and other foreign currency transaction and translation adjustments that affect cash flows are reported in net income, along with related hedge and tax effects.

Goodwill and Other Intangibles - Policy

Goodwill and Other Intangibles

        Goodwill and other intangible assets include the cost of acquired subsidiaries in excess of the fair value of the net tangible assets recorded in connection with acquisitions. Goodwill and indefinite-lived intangible assets are not amortized. Rather, they are tested for impairment during the third quarter each year, or more frequently if events or changes in circumstances indicate that the asset might be impaired. Goodwill is tested at the reporting unit level, which is a business one level below the operating segment, if financial information is prepared and regularly reviewed by management at that level. Once goodwill has been assigned to a reporting unit, it is no longer associated with a particular acquisition; therefore, all of the activities within a reporting unit, whether acquired or organically grown, are available to support the goodwill value. Impairment testing for indefinite-lived intangible assets consists of a comparison of the fair value of the intangible asset with its carrying value.

        Intangible assets with a finite useful life are amortized as related benefits emerge and are reviewed periodically for indicators of impairment in value. If facts and circumstances suggest possible impairment, the sum of the estimated undiscounted future cash flows expected to result from the use of the asset is compared to the current carrying value of the asset. If the undiscounted future cash flows are less than the carrying value, an impairment loss is recognized for the excess of the carrying amount of assets over their fair value.

Earnings Per Common Share - Policy

Earnings Per Common Share

        Basic earnings per common share is calculated by dividing income available to common stockholders by the weighted-average number of common shares outstanding for the period and excludes the dilutive effect of equity awards. Diluted earnings per common share reflects the potential dilution that could occur if dilutive securities, such as options and non-vested stock grants, were exercised or resulted in the issuance of common stock.\