Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets
Fixed maturities, available-for-sale (2013 and 2012 include $243.3 million and $194.6 million related to consolidated variable interest entities)	$ 48,914.9	$ 50,939.3
Fixed maturities, trading (2013 and 2012 both include $110.4 million related to consolidated variable interest entities)	572.9	626.7
Equity securities, available-for-sale	114.0	136.5
Equity securities, trading	666.2	252.8
Mortgage loans	11,868.1	11,519.7
Real estate	1,278.6	1,180.3
Policy loans	859.6	864.9
Other investments (2013 and 2012 include $72.6 million and $80.3 million related to consolidated variable interest entities and $140.5 million and $113.9 million measured at fair value under the fair value option)	2,994.0	3,291.1
Total investments	67,268.3	68,811.3
Cash and cash equivalents	1,707.1	4,177.2
Accrued investment income	571.2	584.4
Premiums due and other receivables	1,160.7	1,084.4
Deferred acquisition costs	3,007.6	2,590.0
Property and equipment	479.1	464.2
Goodwill	1,127.5	543.4
Other intangibles	1,497.4	914.7
Separate account assets (2013 includes $31,999.2 million related to consolidated variable interest entities)	123,800.5	81,653.8
Other assets	1,068.0	1,006.8
Total assets	201,687.4	161,830.2
Liabilities
Contractholder funds	36,402.7	37,786.5
Future policy benefits and claims	22,324.2	22,436.2
Other policyholder funds	753.6	716.4
Short-term debt	175.5	40.8
Long-term debt	2,593.3	2,671.3
Income taxes currently payable	7.9	15.3
Deferred income taxes	634.6	600.0
Separate account liabilities (2013 includes $31,999.2 million related to consolidated variable interest entities)	123,800.5	81,653.8
Other liabilities (2013 and 2012 include $320.6 million and $302.9 million related to consolidated variable interest entities, of which $102.2 million and $85.0 million are measured at fair value under the fair value option)	5,387.2	6,146.1
Total liabilities	192,079.5	152,066.4
Redeemable noncontrolling interest	234.5	60.4
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 458.0 million and 453.5 million shares issued, and 293.9 million and 293.8 million shares outstanding in 2013 and 2012	4.6	4.5
Additional paid-in capital	9,749.3	9,730.9
Retained earnings (accumulated deficit)	5,249.9	4,862.0
Accumulated other comprehensive income (loss)	(17.7)	640.3
Treasury stock, at cost (164.1 million and 159.7 million shares in 2013 and 2012)	(5,707.8)	(5,554.4)
Total stockholders' equity attributable to Principal Financial Group, Inc.	9,278.4	9,683.4
Noncontrolling interest	95.0	20.0
Total stockholders' equity	9,373.4	9,703.4
Total liabilities and stockholders' equity	201,687.4	161,830.2
Series A
Stockholders' equity
Preferred stock, value
Series B
Stockholders' equity
Preferred stock, value	$ 0.1	$ 0.1