Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Fixed maturities, available-for-sale (2013 and 2012 include $272.0 million and $194.6 million related to consolidated variable interest entities)	$ 48,757.1	$ 50,939.3
Fixed maturities, trading (2013 and 2012 both include $110.4 million related to consolidated variable interest entities)	563.1	626.7
Equity securities, available-for-sale	110.5	136.5
Equity securities, trading (2013 includes $327.2 million related to consolidated variable interest entities)	716.9	252.8
Mortgage loans	11,533.6	11,519.7
Real estate	1,271.6	1,180.3
Policy loans	859.7	864.9
Other investments (2013 and 2012 include $68.1 million and $80.3 million related to consolidated variable interest entities and $142.9 million and $113.9 million measured at fair value under the fair value option)	2,944.4	3,291.1
Total investments	66,756.9	68,811.3
Cash and cash equivalents	2,371.8	4,177.2	2,833.9	1,877.4
Accrued investment income	532.1	584.4
Premiums due and other receivables	1,241.0	1,084.4
Deferred acquisition costs	3,077.0	2,590.0	2,358.1	2,442.2
Property and equipment	500.7	464.2
Goodwill	1,100.3	543.4	482.3
Other intangibles	1,459.0	914.7
Separate account assets (2013 includes $32,824.7 million related to consolidated variable interest entities)	130,018.4	81,653.8
Other assets	1,134.2	1,006.8
Total assets	208,191.4	161,830.2
Liabilities
Contractholder funds	35,958.3	37,786.5
Future policy benefits and claims	22,626.2	22,436.2
Other policyholder funds	758.9	716.4
Short-term debt	150.6	40.8
Long-term debt	2,601.4	2,671.3
Income taxes currently payable	5.2	15.3
Deferred income taxes	824.0	600.0
Separate account liabilities (2013 includes $32,824.7 million related to consolidated variable interest entities)	130,018.4	81,653.8
Other liabilities (2013 and 2012 include $342.4 million and $302.9 million related to consolidated variable interest entities, of which $104.9 million and $85.0 million are measured at fair value under the fair value option)	5,224.2	6,146.1
Total liabilities	198,167.2	152,066.4
Redeemable noncontrolling interest	247.2	60.4	22.2
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 459.3 million and 453.5 million shares issued, and 295.2 million and 293.8 million shares outstanding in 2013 and 2012	4.6	4.5
Additional paid-in capital	9,798.9	9,730.9
Retained earnings (accumulated deficit)	5,405.4	4,862.0
Accumulated other comprehensive income (loss)	183.2	640.3
Treasury stock, at cost (164.1 million and 159.7 million shares in 2013 and 2012)	(5,708.0)	(5,554.4)
Total stockholders' equity attributable to Principal Financial Group, Inc.	9,684.2	9,683.4
Noncontrolling interest	92.8	20.0
Total stockholders' equity	9,777.0	9,703.4	9,306.2	9,246.8
Total liabilities and stockholders' equity	208,191.4	161,830.2
Series A
Stockholders' equity
Preferred stock, value
Total stockholders' equity	0	0	0	0
Series B
Stockholders' equity
Preferred stock, value	0.1	0.1	0.1
Total stockholders' equity	$ 0.1	$ 0.1	$ 0.1	$ 0.1