Consolidated Statements of Financial Position - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Assets
Fixed maturities, available-for-sale (2015 and 2014 include $257.4 million and $278.2 million related to consolidated variable interest entities)	$ 49,966.5	$ 49,670.8
Fixed maturities, trading (2015 and 2014 both include $100.4 million related to consolidated variable interest entities)	686.8	604.6
Equity securities, available-for-sale	104.5	123.0
Equity securities, trading (2015 and 2014 include $640.9 million and $345.3 million related to consolidated variable interest entities)	1,202.7	840.2
Mortgage loans	12,339.4	11,811.6
Real estate (2015 and 2014 include $354.5 million and $284.9 million related to consolidated variable interest entities)	1,451.8	1,344.6
Policy loans	817.1	829.2
Other investments (2015 and 2014 include $29.5 million and $40.6 million related to consolidated variable interest entities and $53.4 million and $127.2 million measured at fair value under the fair value option)	3,251.7	3,209.8
Total investments	69,820.5	68,433.8
Cash and cash equivalents	2,564.8	1,863.9
Accrued investment income	545.6	505.9
Premiums due and other receivables	1,429.3	1,213.0
Deferred acquisition costs	3,276.1	2,993.0
Property and equipment	633.8	590.2
Goodwill	1,009.0	1,007.4
Other intangibles	1,359.2	1,323.5
Separate account assets (2015 and 2014 include $33,300.4 million and $34,655.4 million related to consolidated variable interest entities)	136,978.9	140,072.8
Other assets	1,068.7	1,083.5
Total assets	218,685.9	219,087.0
Liabilities
Contractholder funds (2015 includes $338.9 million related to consolidated variable interest entities)	35,716.1	34,726.7
Future policy benefits and claims	25,856.5	24,036.6
Other policyholder funds	805.4	812.7
Short-term debt	181.1	28.0
Long-term debt (2015 and 2014 include $42.8 million and $82.3 million related to consolidated variable interest entities)	3,290.8	2,531.2
Income taxes currently payable	18.4	11.5
Deferred income taxes	697.2	1,035.3
Separate account liabilities (2015 and 2014 include $33,300.4 million and $34,655.4 million related to consolidated variable interest entities)	136,978.9	140,072.8
Other liabilities (2015 and 2014 include $345.9 million and $344.0 million related to consolidated variable interest entities, of which $68.1 million and $71.0 million are measured at fair value under the fair value option)	5,678.4	5,542.2
Total liabilities	209,222.8	208,797.0
Redeemable noncontrolling interest	85.7	58.0
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 466.2 million and 462.7 million shares issued, and 291.4 million and 293.9 million shares outstanding in 2015 and 2014	4.7	4.6
Additional paid-in capital	9,544.8	9,945.5
Retained earnings (accumulated deficit)	6,875.9	6,114.1
Accumulated other comprehensive income (loss)	(882.5)	50.4
Treasury stock, at cost (174.8 million and 168.8 million shares in 2015 and 2014)	(6,231.3)	(5,930.7)
Total stockholders' equity attributable to Principal Financial Group, Inc.	9,311.6	10,184.0
Noncontrolling interest	65.8	48.0
Total stockholders' equity	9,377.4	10,232.0
Total liabilities and stockholders' equity	$ 218,685.9	$ 219,087.0
Series A
Stockholders' equity
Preferred stock, value
Series B
Stockholders' equity
Preferred stock, value		$ 0.1