Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets
Fixed maturities, available-for-sale (2015 and 2014 include $266.4 million and $278.2 million related to consolidated variable interest entities)	$ 49,755.7	$ 49,670.8
Fixed maturities, trading (2015 and 2014 both include $100.4 million related to consolidated variable interest entities)	574.0	604.6
Equity securities, available-for-sale	144.9	123.0
Equity securities, trading (2015 and 2014 include $352.3 million and $345.3 million related to consolidated variable interest entities)	875.1	840.2
Mortgage loans	11,899.5	11,811.6
Real estate (2015 and 2014 include $297.8 million and $284.9 million related to consolidated variable interest entities)	1,391.7	1,344.6
Policy loans	826.0	829.2
Other investments (2015 and 2014 include $34.6 million and $40.6 million related to consolidated variable interest entities and $57.5 million and $127.2 million measured at fair value under the fair value option)	3,395.6	3,209.8
Total investments	68,862.5	68,433.8
Cash and cash equivalents	1,452.0	1,863.9
Accrued investment income	531.1	505.9
Premiums due and other receivables	1,230.0	1,213.0
Deferred acquisition costs	3,020.8	2,993.0
Property and equipment	607.4	590.2
Goodwill	981.0	1,007.4
Other intangibles	1,291.2	1,323.5
Separate account assets (2015 and 2014 include $35,319.4 million and $34,655.4 million related to consolidated variable interest entities)	143,505.2	140,072.8
Other assets	1,013.7	1,083.5
Total assets	222,494.9	219,087.0
Liabilities
Contractholder funds	34,173.8	34,726.7
Future policy benefits and claims	24,377.1	24,036.6
Other policyholder funds	853.1	812.7
Short-term debt	27.2	28.0
Long-term debt (2015 and 2014 include $65.6 million and $82.3 million related to consolidated variable interest entities)	2,514.6	2,531.2
Income taxes currently payable	12.0	11.5
Deferred income taxes	968.5	1,035.3
Separate account liabilities (2015 and 2014 include $35,319.4 million and $34,655.4 million related to consolidated variable interest entities)	143,505.2	140,072.8
Other liabilities (2015 and 2014 include $335.9 million and $344.0 million related to consolidated variable interest entities, of which $67.1 million and $71.0 million are measured at fair value under the fair value option)	5,506.3	5,542.2
Total liabilities	211,937.8	208,797.0
Redeemable noncontrolling interest	65.0	58.0
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 464.7 million and 462.7 million shares issued, and 294.4 million and 293.9 million shares outstanding in 2015 and 2014	4.6	4.6
Additional paid-in capital	9,975.6	9,945.5
Retained earnings (accumulated deficit)	6,420.4	6,114.1
Accumulated other comprehensive income (loss)	28.0	50.4
Treasury stock, at cost ( 170.3 million and 168.8 million shares in 2015 and 2014)	(6,006.1)	(5,930.7)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,422.6	10,184.0
Noncontrolling interest	69.5	48.0
Total stockholders' equity	10,492.1	10,232.0
Total liabilities and stockholders' equity	222,494.9	219,087.0
Series A
Stockholders' equity
Preferred stock, value
Series B
Stockholders' equity
Preferred stock, value	$ 0.1	$ 0.1