2.4.0.82010 - Disclosure - Nature of Operations and Significant Accounting Policies (Policies)truefalsefalse1false falsefalseD2013Q2YTDhttp://www.sec.gov/CIK0001126328duration2013-01-01T00:00:002013-06-30T00:00:001true 1pfg_NatureOfOperationsAndSignificantAccountingPoliciesDisclosureAbstractpfg_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Nature of Operations and Significant Accounting Policies2false 2us-gaap_PolicyholderAccountsPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> 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 statements 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 non-domestic 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 June 30, 2013 and December 31, 2012, the separate account assets include a separate account valued at $181.6 million and $148.3 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.   </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for contracts reported in separate accounts, including the extent and terms of minimum guarantees, basis of presentation for separate account assets and liabilities and related separate account activity, the liability valuation method and assumptions used in valuing each type of policyholder and contract holder account maintained by the entity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 80 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 03-1 -Paragraph 38 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Separate Accounts - PolicyfalseNature of Operations and Significant Accounting Policies (Policies)UnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://principal.com/role/DisclosureNatureOfOperationsAndSignificantAccountingPoliciesPolicies12