Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Assets
Fixed maturities, available-for-sale (2012 and 2011 include $194.9 million and $214.2 million related to consolidated variable interest entities)	$ 49,501.3	$ 49,006.7
Fixed maturities, trading (2012 and 2011 both include $132.4 million related to consolidated variable interest entities)	868.7	971.7
Equity securities, available-for-sale	138.4	77.1
Equity securities, trading (2012 and 2011 include $321.4 million and $207.6 million related to consolidated variable interest entities)	536.4	404.8
Mortgage loans	11,308.9	10,727.2
Real estate	1,111.9	1,092.9
Policy loans	873.9	885.1
Other investments (2012 and 2011 include $90.5 million and $97.8 million related to consolidated variable interest entities, of which $89.8 million and $97.5 million are measured at fair value under the fair value option)	2,952.5	2,985.8
Total investments	67,292.0	66,151.3
Cash and cash equivalents (2012 and 2011 include $209.1 million and $317.7 million related to consolidated variable interest entities)	1,651.9	2,833.9
Accrued investment income	622.5	615.2
Premiums due and other receivables	1,118.8	1,196.5
Deferred policy acquisition costs	2,665.6	2,428.0
Property and equipment	476.7	457.2
Goodwill	490.7	482.3
Other intangibles	893.9	890.6
Separate account assets	77,566.5	71,364.4
Other assets	959.6	942.3
Total assets	153,738.2	147,361.7
Liabilities
Contractholder funds	36,922.5	37,676.4
Future policy benefits and claims	20,604.0	20,210.4
Other policyholder funds	639.1	548.6
Short-term debt	101.2	105.2
Long-term debt	1,570.8	1,564.8
Income taxes currently payable	2.9	3.1
Deferred income taxes	492.8	208.7
Separate account liabilities	77,566.5	71,364.4
Other liabilities (2012 and 2011 include $555.4 million and $565.2 million related to consolidated variable interest entities, of which $97.8 million and $88.4 million are measured at fair value under the fair value option)	6,086.5	6,286.2
Total liabilities	143,986.3	137,967.8
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 452.4 million and 450.3 million shares issued, and 300.9 million and 301.1 million shares outstanding in 2012 and 2011	4.5	4.5
Additional paid-in capital	9,669.6	9,634.7
Retained earnings (deficit)	4,548.5	4,402.3
Accumulated other comprehensive income (loss)	488.1	258.0
Treasury stock, at cost (151.5 million and 149.2 million shares in 2012 and 2011)	(5,345.9)	(5,281.7)
Total stockholders' equity attributable to Principal Financial Group, Inc.	9,364.9	9,017.9
Noncontrolling interest	387.0	376.0
Total stockholders' equity	9,751.9	9,393.9
Total liabilities and stockholders' equity	153,738.2	147,361.7
Series A
Stockholders' equity
Preferred stock, value
Series B
Stockholders' equity
Preferred stock, value	$ 0.1	$ 0.1