Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Assets
Fixed maturities, available-for-sale (2011 and 2010 include $214.2 million and $257.9 million related to consolidated variable interest entities)	$ 49,006.7	$ 48,636.3
Fixed maturities, trading (2011 and 2010 include $132.4 million and $131.4 million related to consolidated variable interest entities)	971.7	1,120.3
Equity securities, available-for-sale	77.1	169.9
Equity securities, trading (2011 and 2010 include $207.6 million and $158.6 million related to consolidated variable interest entities)	404.8	316.9
Mortgage loans	10,727.2	11,125.1
Real estate	1,092.9	1,063.5
Policy loans	885.1	903.9
Other investments (2011 and 2010 include $97.8 million and $128.7 million related to consolidated variable interest entities, of which $97.5 million and $128.3 million are measured at fair value under the fair value option)	2,988.0	2,641.6
Total investments	66,153.5	65,977.5
Cash and cash equivalents (2011 and 2010 include $317.7 million and $100.0 million related to consolidated variable interest entities)	2,833.9	1,877.4
Accrued investment income	615.2	666.1
Premiums due and other receivables	1,245.2	1,063.0
Deferred policy acquisition costs	3,313.5	3,529.8
Property and equipment	457.2	458.7
Goodwill	482.3	345.4
Other intangibles	890.6	834.6
Separate account assets	71,364.4	69,555.3
Other assets	942.2	1,323.3
Total assets	148,298.0	145,631.1
Liabilities
Contractholder funds	37,676.4	37,301.1
Future policy benefits and claims	20,207.9	20,046.3
Other policyholder funds	543.7	592.2
Short-term debt	105.2	107.9
Long-term debt	1,564.8	1,583.7
Income taxes currently payable	3.1	6.2
Deferred income taxes	533.4	409.9
Separate account liabilities	71,364.4	69,555.3
Other liabilities (2011 and 2010 include $565.2 million and $433.6 million related to consolidated variable interest entities, of which $88.4 million and $114.5 million are measured at fair value under the fair value option)	6,286.1	6,143.5
Total liabilities	138,285.0	135,746.1
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 450.3 million and 448.5 million shares issued, and 301.1 million and 320.4 million shares outstanding in 2011 and 2010	4.5	4.5
Additional paid-in capital	9,634.7	9,563.8
Retained earnings (deficit)	5,077.5	4,612.3
Accumulated other comprehensive income (loss)	201.9	272.4
Treasury stock, at cost (149.2 million and 128.1 million shares in 2011 and 2010)	(5,281.7)	(4,725.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	9,637.0	9,727.8
Noncontrolling interest	376.0	157.2
Total stockholders' equity	10,013.0	9,885.0
Total liabilities and stockholders' equity	148,298.0	145,631.1
Series A
Stockholders' equity
Preferred stock, value
Series B
Stockholders' equity
Preferred stock, value	$ 0.1	$ 0.1