Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets
Fixed maturities, available-for-sale (2012 and 2011 include $180.3 million and $214.2 million related to consolidated variable interest entities)	$ 51,533.9	$ 49,006.7
Fixed maturities, trading (2012 and 2011 both include $132.4 million related to consolidated variable interest entities)	808.0	971.7
Equity securities, available-for-sale	143.6	77.1
Equity securities, trading (2012 and 2011 include $0.0 million and $207.6 million related to consolidated variable interest entities)	237.6	404.8
Mortgage loans	11,297.9	10,727.2
Real estate	1,208.6	1,092.9
Policy loans	866.6	885.1
Other investments (2012 and 2011 include $81.3 million and $97.8 million related to consolidated variable interest entities and $114.2 million and $97.5 million measured at fair value under the fair value option)	3,172.1	2,985.8
Total investments	69,268.3	66,151.3
Cash and cash equivalents (2012 and 2011 include $0.0 million and $317.7 million related to consolidated variable interest entities)	2,279.0	2,833.9
Accrued investment income	614.4	615.2
Premiums due and other receivables	1,192.2	1,196.5
Deferred policy acquisition costs	2,558.5	2,428.0
Property and equipment	468.4	457.2
Goodwill	548.9	482.3
Other intangibles	927.4	890.6
Separate account assets	80,160.5	71,364.4
Other assets	1,175.7	942.3
Total assets	159,193.3	147,361.7
Liabilities
Contractholder funds	37,312.2	37,676.4
Future policy benefits and claims	21,952.0	20,210.4
Other policyholder funds	720.8	548.6
Short-term debt	28.5	105.2
Long-term debt	2,180.0	1,564.8
Income taxes currently payable	6.6	3.1
Deferred income taxes	951.5	208.7
Separate account liabilities	80,160.5	71,364.4
Other liabilities (2012 and 2011 include $312.5 million and $565.2 million related to consolidated variable interest entities, of which $96.4 million and $88.4 million are measured at fair value under the fair value option)	5,974.3	6,286.2
Total liabilities	149,286.4	137,967.8
Redeemable noncontrolling interest	61.0	22.2
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 453.3 million and 450.3 million shares issued, and 293.6 million and 301.1 million shares outstanding in 2012 and 2011	4.5	4.5
Additional paid-in capital	9,712.2	9,634.7
Retained earnings (accumulated deficit)	4,784.3	4,402.3
Accumulated other comprehensive income (loss)	880.8	258.0
Treasury stock, at cost (159.7 million and 149.2 million shares in 2012 and 2011)	(5,554.4)	(5,281.7)
Total stockholders' equity attributable to Principal Financial Group, Inc.	9,827.5	9,017.9
Noncontrolling interest	18.4	353.8
Total stockholders' equity	9,845.9	9,371.7
Total liabilities and stockholders' equity	159,193.3	147,361.7
Series A
Stockholders' equity
Preferred stock, value
Series B
Stockholders' equity
Preferred stock, value	$ 0.1	$ 0.1